Why Solidworks doesn't allow me using Bend Deduction for hems?

I'm working on a sheet metal and am trying to add a hem. When I try Bend Deduction, Solidworks throws the following error and asks me to use K-Factor instead. I've been using K-factor for hems up to now, but for this particular part I need to use bend Deduction. Is there any way to satisfy SW to accept Bend Deduction?

Thanks for any kind of advice.

SolidworksGeneral