SEM texture spray

I made a gauge pod out of fiberglass and the shape turned out great, but I am having major problems putting a finish on it.  I want it to look like the oem finish which is a textured ABS look.  I am using SEM texture spray to create the texture.  When I first spray it on, it is too rough so I need to sand it down.  When I do this it sands very unevenly and creates shiney spots when I paint it where the texture has worn away.  I've resprayed and repeated this at least 10 times each time trying different things.  I've tried sanding with 1500,1000,800.400,220 grit papers.  All produced the same splotchy uneven texture.  I have tried sanding it with and without a sanding block, its the same result.  One idea I am considering is maybe I need to use an adhesion promotor to get it to stick better so it will sand more evenly, but I doubt it since I am applying the texture over a coat of SEM primer. 

I would upload pics, but they are too large for the 30kB maximum.