Hi Seetha,
Reference: - “We have changed business partner (vendor) from certain date.”
Please check start relationship date of new business partner which you had added in contract, this start relationship date should not be before the date of the posted cash flow period. If you change anything in between of the period which already had been posted system will generate differential value to post.
In your case you had posted the cash flow for BP1 now you had changed it to BP2, system create the reversal posting for BP1 and open periodic posting for BP2.
Activity:
Change start relationship date of new BP in partner tab
Change date (time-dependent) for BP in posting parameter tab for Posting & withholding tax (if assigned to condition)
Best Regards
Sudhir