Rattle can? Not the best choice since you can't see the amount of evenness in the solution.
Appropriate level of thinning? Should have the consistency of milk, at most, before airbrushing.
Temperature? Especially for rattle cans. Too cold will leavea too glossy finish. The stuff dries fast enough to test it on scrap before committing it to your finished work.
Bad batch? Always a possibility.
Home Depot? Where does that say Hobby? Avoid it. "Stuff in a bottle turns your models yellow? What stuff is that?
I've used Testors Dullcote (and Glosscote) for years witout a problem. Well mixed dull gives an absolutely dead flat finishe when airbrushed properly. Enough so that I can use a variety of paint finishes before dullcoating and I regularly take figure awards throughout the region.