Check Function Module is not working

Hi All Expert,

I'm new in workflow and  develop custom workflow for Transaction FB65 ( Vendor Credit Memo) and using business object FIPP , event CREATED.

Actually  requirement is that when user  click on park button in FB65 then should  be trigger workflow only for particular vendor code .

Now my workflow is working fine for all vendor code.

For particular vendor code, I have created an new entries in  SWE2 and assigning a check function module to that

Refer Link :         http://www.****************/Tutorials/Workflow/checkfunctionmodule/demo.htm

and also same entries create in SWETYPV But Check Function Module is not working before workflow trigger.

Appreciate your help and support.

Regards

Saurabh