Hi Sonalkar,
UD reversal is not a standard process.
According to you screen shots you are only entering inspection lot in the ZTCODE.
Error is suggesting that you have shortfall of 3420 qty in pre. period.
According to your MB51 screen shot 3420 qty is withdrawn on 28.02.2016.
Can you confirm with abaper which posting date(BUDAT) is used in the ZTCODE to post the reversal?
May be revesal date is not current date.
Regards,
Amarnath Dube