VBOF error--"Incorrect doc.no.:XXXX. Select document number between YYYY and ZZZZZ"

Hello Friends,

After running VBOF i am getting error message-"Incorrect doc.no.:XXXX. Select document number between YYYY and ZZZZZ" . Here before running VBOF , in selection screen i have put the posting date as today's date and the billing documents to be considered are from the month of March'14 . In rebate agreement created recently in April'14, validity date is from 1st to 31st March 2014. Please tell me what must be causing this error .

Regards,

Sandeep