Duct sealant problems

Hello everyone,
After many weeks of deliberation, I have elected to seal my ductwork with MasterFlow mastic. It works like a charm! However, when it came time to insulate over the mastic, I ran into trouble.

It looks like pretty much all types of foil duct tape do not stick to dried mastic. I can't keep the stuff on the ducts where it meets mastic. Any thoughts on this issue?

Thanks!