object for VBAP - VBAK

Hello,

I need to catch (by event, user exit, BADI,...) the changes occurred in VBAP & VBAK to be transferred to other system by XI.

I tried to turn on the event for object VBAP, but no event was triggered after changed or created (via transaction VA52).

Doe's anyone know how can I do it??

Thanks in advance for any help,

Fariba