Hi,

I've only had 100% success when I started buying ALL the necessary stuff from MiniCraft in Florida. They sell gelcoat that can be sprayed with a normal sprayer and cures in air in 30 minutes. NEVER use acetone to thin. Minicraft sells a spray reducer that works perfectly. See: http://www.minicraft.com. Call them and they will set you up with everything. Unfortunately it sounds like your prior work will have to be removed. If it didn't kick by now, it's not going to.

P.S. They also sell tints that can get you an exact color match. I did 9 large areas on a 31 foot boat and now I can't even find where they were.