I figured it out.  ProSeries gives an error when entering Foreign Transactions info on the 1065 K-1 worksheet if entering both Passive and General income categories, and directs you to split these out into separate K-1s.  When I removed the box 16, codes F and M data and entered just those two data elements to a separate K-1, the Form 1116 reverted back to the General Category Income selection.  I was then able to enter my FTC carryover data without any errors.