DMAAI 3280 Invalid errors when Manufactured item is setup with "W" line type instead of an "S"

Manufacturing experts:

We are testing a new way to build our custom items.  We are using a "W" line type on the Sales Order, to generate the Work Order.  This works fine.  We thought we should save a step and on the Item Branch make the Line Type "W".  Now we get a DMAAI error when we run Variance Accounting [R31804].  Have any of you ever noticed this?  The 3260 and 3280 both look like they are set up correctly.  When we changed the Line Type in the Item Branch [F41026] back to an "S", then we don't get the DMAAI errors.