PBO issue

Hi,

The issue is, I am validating some data based on standard transaction SAVE button, in case of in-valid, i'm displaying the error message. Now after the error message the screen got locked, even if I press 'enter' or any user action..screen got locked. In my validation i have written the logic for sy-ucomm = 'SAVE'. But the issue is, after displaying the error message, in the next user action..sy-ucomm would not changed, i think becuase of PBO is not getting called. When i hit enter second time, then it works fine. Is there any way to check in the validation that PBO is called or not, so I can skip the error message in case when sy-ucomm = save and screen has not completed the PBO cycle.

(I am also trying to write the code at some other appropriate place, but could not find the place and it's a standard SAP code)

Thanks,