sounds like you may have laid the coats down too thick, and not let each coat cure enough... also, you maybe have used say, cellulose paint, and acryclic clearcoat, and that would mess things up at the end...
after spending way too much money on rattlecans myself, and having a nightmare with working with spraycans as opposed to real paint, i'd advise just taking it to someone with a compressor and paint gun, whether it's something they have at their house, or at work... it would have been cheaper, and a lot less hassle for me to pay someone to auto-paint my case...
also, i still haven't finished it

(i know how to paint with rattlecans... i just don't have a workshop or garage or ANYwhere to paint unless i want to sacrifice a corner of my bedroom and sleep in a cloud of cellulose fumes lol...)