Hi Bhargava,
The FM which you created, has this been mapped in table TPS34? If yes , the Z FM should have interface structure same as OPEN_FI_PERFORM_CRM0_200_P? It should trigger then. As a starting point you can start the debug from FM - CRS_SEND_TO_SERVER , Inside it we have call to OPEN_FI_PERFORM_CRM0_200_P . This FM calls the entry which we maintained in TPS34.
To maintain TPS34 table follow like below.
Transaction: FIBF--> Setting->Process Modules ...of a Cusomer.
BR/Himayat.