You may need to wait until the bid month opens and then try to drop the carry over reserve days.

Section 7E2b: You needed to slide your vacation in May to conflict with the carry in before the April bidmonth.

You can't expand to take out carry in (as I read it) and you have to slide the month prior, so you would have had to have slid your May vacation prior to the April bid month. Not sure why or how you do that, but I think that is the problem.