There is a silver rod with a gear on the end of it that rests on the film spool. That may be bent and not riding on the film properly to activate the counter mechanism.

If you say the wheel does count as you turn it then the other common problem is the small tab that gets pushed in on the door edge, it may be stuck or not hitting the edge properly. That tab resets the counter to zero (S) when the door is opened.

Hope this helps.