Updating Custom Fields for VA02

hi,

My scenario is to create a custom screen for sales order header in additional tab B and during saving the custom fields has to be updated in a u2018Zu2019 table. Since access key was not provided, Iu2019m calling the screen as a pop-up screen from an enhancement spot.

For saving the sales order i use MV45AFZZ  USEREXIT_SAVE_DOCUMENT. VA01 it is working perfectly but for VA02 the form USEREXIT_SAVE_DOCUMENT is not triggering. I have not enhanced any fields in VBAK or VBAP. For temporary purpose, iu2019m passing a value in a header field which is not used.

is there any solution for resolving the issue.

Regards,

Senthil