delegatecall for Smart Contract versioning

Question

I've a state variable

address public current;

which stores the address of the latest updated contract. This value can be modified with a function.

Then, I've a function of this kind

  function example(string param1, string param2, string param3, uint256 param4) public {
    if (current == address(this)) {
      do things...
    }
    else {
      current.delegatecall(bytes4(sha3("example(string,string,string,uint256)")), param1, param2, param3, param4);
    }
  }

Obviously, the new contract has the function example with the same signature of the older version. However, when I try to call this function in Remix with current=another_address, the transaction does not modify the storage of the calling contract. It's as if it did nothing.

Am I doing something wrong?

Thank you.