DeathProof, that's a little cold. It may be as simple as that. Temperature can really screw with this stuff.
Dullcote over a clear gloss shouldn't be any different than putting it over a glossy paint, which we do all the time. But you can always run into problems with multiple layers of different types of paint. Incompatible brands, not allowing layers to cure, etc. I used Dullcote on something when it was really humid and it dried white from all the moisture in the air.
