Problem with threads

I’m sure this is a nwebie error, I’m trying to make a multithreaded program
and I can’t seem to figure out what type the thread function should be.

From example programs, it looks like this:
int threadFunction(void * data);

then when it’s called:
SDL_CreateThread(threadFunction, NULL);

but when I do this I get:
no matches converting function tLogon' to typeint ()(void)

what am I doing wrong?