Enhancing a Z-function module.

Hi,

I am trying to extend a FM - ROS_BUPA_CREATE_PROSP.....which contains a BAdi for making fields mandatory in a BSP application.

But I need to modify the Z-copy of this function module for putting in a required structure that I have a requirement for.

How do I go about it., as the copied FM module, on checking for syntax, gives me error saying that the BAdi doesnt exist, where as I have not even touched the BAdi.

Regards,

Gautam