Flat Amount Benefit DBA not getting Calculated in Pre-payroll

Hi Team, I am having  issue while running Payroll with Falt Amount Benefit Code. Instead of Falt amount  if i use method of cacculation as % it work but for $ it does not work. In simple none of the Flat Amount DBA is getting calculated in the system. If same flat amount benefit code used in OTO,it works fine. Can someone help what could be missing at our end? Do i need to check record count of F07901? Thanks, Kirit