In order to find out what is going wrong (it must be one of the field values of the line in the account schedule that is giving you the error), then do this:
- From the account schedule line before showing correct value: Ctrl-Alt-F1 (About this page). Here you can see the actual table content. Export to Excel.
- From the account schedule line after you have edited it to show the correct value: Ctrl-Alt-F1 (About this page). Here you can see the actual table content. Export to Excel.
- Compare the Table fields in the two Excel sheets to see which fields are different = causing the problem.
Eventually attach the two files to your reply.