VOPT32.DLL must contain an exported function declared in VSUSER.H in the following format:
int FAR EXPORT USER_OPT_FUNC(DOUBLE *unknownVec, int unknownCount, int costCount, int globalConstraintCount);
The exported function be must be named OptimizeEvent.
Before you initiate global optimization, make sure the User Method parameter in the dialog box for the System > Optimization Properties is activated.