Why transfer funds breaks contract?

Question

My deployed contract called successfully only by "function invocation" through web3 or Remix. But it always failed when I sending funds to the contract.

I thought that only requirement that contract has payable function but maybe it is not enough?

Contract looks like:

contract GetRandom is usingOraclize {
    event newRandomNumber(bytes);

    function GetRandom() {
        oraclize_setProof(proofType_Ledger);
        update();
    }

    function __callback(bytes32 _queryId, string _result, bytes _proof) oraclize_randomDS_proofVerify(_queryId, _result, _proof) {
        // if we reach this point successfully, it means that the attached authenticity proof has passed!
        if (msg.sender != oraclize_cbAddress()) throw;

        newRandomNumber(bytes(_result));
    }

    function update() payable {
        uint N = 7; // number of random bytes we want the datasource to return
        uint delay = 0; // number of seconds to wait before the execution takes place
        uint callbackGas = 200000; // amount of gas we want Oraclize to set for the callback function

        // this function internally generates the correct oraclize_query and returns its queryId
        bytes32 queryId = oraclize_newRandomDSQuery(delay, N, callbackGas);
    }
}

Answer 1

it always failed when I sending funds to the contract

This sounds as if you attempt to send Ether to the smart contract without any further data - and hence without calling any specific function. If you "just send Ether" to the smart contract, a special function without a name called fallback function is invoked. In your case, this fallback function also needs to have a payable modifier. If you do not implement a payable fallback function yourself, it is not possible to "just send Ether" to the smart contract.

Answer 2

Throw this one in as the fallback, similar to what Sebastian said:

function() payable {}