Unless we have the program here, there is little we can tell you.

What is the call stack when you get the crash? You shoud see a series of function calls that lead up to the function that crashes. Examine the call stack to identify the last function that is yours, then examine the arguments that you are passing to this function. Are they legitimate?

Again, we do not have this program, so there is little anyone can do except have you diagnose the problem yourself.
I do not have access to read the dll since it has been provided by a third party.
Then get the makers of the DLL to help you.

Regards,

Paul McKenzie