I finally could create my first test token on Rinkeby. Smart contract is deployed, buyer can send ETHs, the Receiving address receives funds...

Contract address. https://rinkeby.etherscan.io/token/0x4a2f8d4391bfde0bf35b09e5f3e85cb7cdf454e9

However, below issues remain unclear:

  1. Buyer (different test account) made 3 successful transfers to this address. However - where are his tokens? He cant add TOKKA on MetaMask, while TOKKA exists.
  2. Despite 3 transactions all 18 million tokens still belong to holder and TOken Holders include only contract holder? And it says 0% :)

this is the code.

pragma solidity ^0.4.17;

contract ERC20Basic {
  uint256 public totalSupply;
  function balanceOf(address who) public view returns (uint256);
  function transfer(address to, uint256 value) public returns (bool);
  event Transfer(address indexed from, address indexed to, uint256 value);

library SafeMath {
  function mul(uint256 a, uint256 b) internal pure returns (uint256) {
    if (a == 0) {
      return 0;
    uint256 c = a * b;
    assert(c / a == b);
    return c;

  function div(uint256 a, uint256 b) internal pure returns (uint256) {
    // assert(b > 0); // Solidity automatically throws when dividing by 0
    uint256 c = a / b;
    // assert(a == b * c + a % b); // There is no case in which this doesn't hold
    return c;

  function sub(uint256 a, uint256 b) internal pure returns (uint256) {
    assert(b <= a);
    return a - b;

  function add(uint256 a, uint256 b) internal pure returns (uint256) {
    uint256 c = a + b;
    assert(c >= a);
    return c;

contract BasicToken is ERC20Basic {
  using SafeMath for uint256;

  mapping(address => uint256) balances;

  * @dev transfer token for a specified address
  * @param _to The address to transfer to.
  * @param _value The amount to be transferred.
  function transfer(address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[msg.sender]);

    // SafeMath.sub will throw if there is not enough balance.
    balances[msg.sender] = balances[msg.sender].sub(_value);
    balances[_to] = balances[_to].add(_value);
    Transfer(msg.sender, _to, _value);
    return true;

  * @dev Gets the balance of the specified address.
  * @param _owner The address to query the the balance of.
  * @return An uint256 representing the amount owned by the passed address.
  function balanceOf(address _owner) public view returns (uint256 balance) {
    return balances[_owner];


contract ERC20 is ERC20Basic {
  function allowance(address owner, address spender) public view returns (uint256);
  function transferFrom(address from, address to, uint256 value) public returns (bool);
  function approve(address spender, uint256 value) public returns (bool);
  event Approval(address indexed owner, address indexed spender, uint256 value);

contract StandardToken is ERC20, BasicToken {

  mapping (address => mapping (address => uint256)) internal allowed;

   * @dev Transfer tokens from one address to another
   * @param _from address The address which you want to send tokens from
   * @param _to address The address which you want to transfer to
   * @param _value uint256 the amount of tokens to be transferred
  function transferFrom(address _from, address _to, uint256 _value) public returns (bool) {
    require(_to != address(0));
    require(_value <= balances[_from]);
    require(_value <= allowed[_from][msg.sender]);

    balances[_from] = balances[_from].sub(_value);
    balances[_to] = balances[_to].add(_value);
    allowed[_from][msg.sender] = allowed[_from][msg.sender].sub(_value);
    Transfer(_from, _to, _value);
    return true;

   * @dev Approve the passed address to spend the specified amount of tokens on behalf of msg.sender.
   * Beware that changing an allowance with this method brings the risk that someone may use both the old
   * and the new allowance by unfortunate transaction ordering. One possible solution to mitigate this
   * race condition is to first reduce the spender's allowance to 0 and set the desired value afterwards:
   * https://github.com/ethereum/EIPs/issues/20#issuecomment-263524729
   * @param _spender The address which will spend the funds.
   * @param _value The amount of tokens to be spent.
  function approve(address _spender, uint256 _value) public returns (bool) {
    allowed[msg.sender][_spender] = _value;
    Approval(msg.sender, _spender, _value);
    return true;

   * @dev Function to check the amount of tokens that an owner allowed to a spender.
   * @param _owner address The address which owns the funds.
   * @param _spender address The address which will spend the funds.
   * @return A uint256 specifying the amount of tokens still available for the spender.
  function allowance(address _owner, address _spender) public view returns (uint256) {
    return allowed[_owner][_spender];

   * approve should be called when allowed[_spender] == 0. To increment
   * allowed value is better to use this function to avoid 2 calls (and wait until
   * the first transaction is mined)
   * From MonolithDAO Token.sol
  function increaseApproval(address _spender, uint _addedValue) public returns (bool) {
    allowed[msg.sender][_spender] = allowed[msg.sender][_spender].add(_addedValue);
    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;

  function decreaseApproval(address _spender, uint _subtractedValue) public returns (bool) {
    uint oldValue = allowed[msg.sender][_spender];
    if (_subtractedValue > oldValue) {
      allowed[msg.sender][_spender] = 0;
    } else {
      allowed[msg.sender][_spender] = oldValue.sub(_subtractedValue);
    Approval(msg.sender, _spender, allowed[msg.sender][_spender]);
    return true;


contract TOKKA is StandardToken {
    string public name = "TOKKA";
    string public symbol = "TOK";
    uint256 public decimals = 18;

    uint256 constant INITIAL_SUPPLY = 18000000 * 10**18;
    function TOKKA () public {
       balances[msg.sender] = INITIAL_SUPPLY;

contract Crowdsale {
  using SafeMath for uint256;

   // The token being sold
  TOKKA public token;

  // start and end timestamps where investments are allowed (both inclusive)
  uint256 public startTime;
  uint256 public endTime;

  // address where funds are collected
  address public wallet;

  // how many token units a buyer gets per wei
  uint256 public rate;

  // amount of raised money in wei
  uint256 public weiRaised;

  event TokenPurchase(address indexed purchaser, address indexed beneficiary, uint256 value, uint256 amount);

  function Crowdsale(uint256 _startTime, uint256 _endTime, uint256 _rate, address _wallet) public {
    require(_startTime >= now);
    require(_endTime >= _startTime);
    require(_rate > 0);
    require(_wallet != address(0));

    startTime = _startTime;
    endTime = _endTime;
    rate = _rate;
    wallet = _wallet;
    token = createTokenContract();

// creates the token to be sold.
// override this method to have crowdsale of a specific mintable token.
function createTokenContract() internal returns (TOKKA) {
    return new TOKKA();

  // fallback function can be used to buy tokens
  function () external payable {

  // low level token purchase function
function buyTokens(address beneficiary) public payable {
    require(beneficiary != address(0));

    uint256 weiAmount = msg.value;

    // calculate token amount to be created
    uint256 tokens = weiAmount.mul(rate);

    // update state
    weiRaised = weiRaised.add(weiAmount);

    // transfer tokens purchased 
    ERC20(token).transfer(this, tokens);

    TokenPurchase(msg.sender, beneficiary, weiAmount, tokens);


  function forwardFunds() internal {

  function validPurchase() internal view returns (bool) {
    bool withinPeriod = now >= startTime && now <= endTime;
    bool nonZeroPurchase = msg.value != 0;
    return withinPeriod && nonZeroPurchase;

  function hasEnded() public view returns (bool) {
    return now > endTime;


contract CappedCrowdsale is Crowdsale {

  using SafeMath for uint256;

  uint256 public cap;

  function CappedCrowdsale(uint256 _cap) public {
    require(_cap > 0);
    cap = _cap;

  function validPurchase() internal view returns (bool) {
    bool withinCap = weiRaised.add(msg.value) <= cap;
    return super.validPurchase() && withinCap;

  function hasEnded() public view returns (bool) {
    bool capReached = weiRaised >= cap;
    return super.hasEnded() || capReached;


2 Answers 2


Q: Buyer (different test account) made 3 successful transfers to this address.

The contract address on etherscan contains one incoming ether transaction and that too failed.

This could be the error. The crowdsale contract contains TOKKA public token; defining the type of token variable. Also, the contract TOKKA is StandardToken. then, shouldn't this line

// transfer tokens purchased 
ERC20(token).transfer(this, tokens);


// transfer tokens purchased 
StandardToken(token).transfer(beneficiary, tokens);

Q: where are his tokens?

All the tokens are in the same account 0x9a5f88309e354ed6b0989cea3a680e1bb2ab4bc5. All the three transfer of tokens has same from and to address.

Q: He cant add TOKKA on MetaMask, while TOKKA exists.

The name of the Token is TOKKA. but the token symbol is TOK. Anyways the best way to add a token is using the address. In metamask once you put in the token address 0x4a2f8d4391bfde0bf35b09e5f3e85cb7cdf454e9 It will automatically fill in the rest of the details.


All the transfers seem to have the same from and to address (the token contract). I believe the issue is this line in buyTokens:

ERC20(token).transfer(this, tokens);

Shouldn't that read as follows?

ERC20(token).transfer(beneficiary, tokens);
  • As per smarx comments, I made that little change in the code. Below is the new contract. Buyer is shown in the Token Holders. In MetaMask buyer sees his tokens. Thanks guys. Send some test ETHs..let me know how it goes rinkeby.etherscan.io/token/… LET ME KNOW IF THIS SMART CODE IS FINE NOW? The only thing is CappedCrowdsale. The contract it there but I DONNOW HOW TO ENTER HARD CAP VALUE? CAN I ENTER IN Crowdsale OF CREATE IN THE RUN?
    – Buzzmuzz5
    Dec 19, 2017 at 19:00
  • A comment isn't a good place to ask unrelated questions. Please create a new question if you want to ask something else.
    – user19510
    Dec 19, 2017 at 19:11

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