NOOB Error : Transaction mined but execution failed

Question

i´m learning Solidity now, and i saw this code on web but when i try to use the method "Deposito" i receive a error. Someone knows what's that ? (PS.: I try to put the value but every time i chose another value different from 0 don't work).

I was using the remix to test code.

pragma solidity ^0.4.2;

CODE:

mapping (address => uint) private saldos;

function deposito() public returns (uint) {
    saldos[msg.sender] += msg.value;

    // Sem necessidade de "this." ou "self." para variáveis de estado
    // todos as variáveis são inciadas com seu valor default

    LogRealizacaoDeDeposito(msg.sender, msg.value); // dispara evento

    return saldos[msg.sender];
}