Bend Allowance calculation

Hi,
I was wondering if anyone could help on my problem.
I have problem on using SW bend Allowance, the total length from SWcalculation is always different with the total length frommanufacture calculation.
The manufacuter use DRC (Dynamic Research Corporation) Machine tobend the sheet and use the following calculation;
Total length = (A+B) - (2 BA)(No 90o Bend)
A= length from edge sheet to outside edge bend
B= Length from outside edge bend to the other edge of the sheet

Currently I have to enter manual bend deduction to match the resultfrom the manufacture.
By the way, I have the guide "DRC Automatic Back Guage System BendAllowance" from manufacture and I could attached it if needed

Thanks
KardonoSolidworksSheet Metal