When the file name ends in ".obj" The line number is usually always 1. The part in bold is what you are looking for. The rest is the compiler's way of defining the return type, if any, and the parameters, if any. All that part for the parameters is sometimes important, but usually not the problem.
Most times I find that there is a spelling problem. This could start in the class definition or at the function definition.
Another possibility is that you forward declared the function in the class, but did not define the function.
Without seeing the code it is hard to say where the problem is.