To overload a function in C++ you have the same name but different variables (this can be different variables as in an int instead of double) or a different number of variables present. Any combination of these two works as well. If the error is correct (not holding my breath) it means your inputting the wrong variables compared to what is expected.

EDIT: Please note if the error is what I said it is, it would fail at compile time, if it is within the game, then the error would possibly occur when you first try to use the function, assuming at least one of those functions work.

My original suggestion I believe is still valid (unless you tried it already) please humor me and create a function that accepts doubles and ints and if they don't work, the error is incorrect. Then you'll have to look at other options.

In response to an earlier comment of yours, I'm not sure what function does but putting void, int, double etc. in front of your function simply tells the function that you are returning that kind of variable within the function. Unless you are returning something I suggest you stick with function or void. But you previously said you've tried both options so this is just an FYI to anyone who is confused on the matter.

EDIT: What call works and what call doesn't by the way? I'm curious.

EDITx2: The reason it may be bugging out on you is when you simply input 15 or "a message" into a function, the compiler is up to its own devices to figure out what that is, just because you want it to be a var doesn't mean it will be passed as such (in this case it should be an int I believe)