Read data from SAP BP Screen with BDT event DCHCK

Hi

I have Implemented a code in DCHCK event to validate EEWB-Zfield value , But I'm not able to Capture the values entered by user in the BP Screen.

The FM's BUP_BUPA_MEMORY_GET_ALL ,BUA_BUPA_MEMORY_GET are not retrieving the values to tables.

Could any one tell me How to capture the values on BP Screen.

Thanks