Tamiya X22 Clear

G'day guys, I have a question about Tamiya X22 Clear. When I try to use this stuff as a glossy coat before decalling I find it difficult to achieve a nice smooth glossy layer. I'm thinning with Tamiya thinner at 50/50 but find if I try to "build" a coat in layers I get a very rough sandpaper type surface texture. The only way I can get something resembling a smooth texture is to try for a heavy coat where it almost seems to be on the verge of running but the clear seems to need this so as to level itself for smoothness. I don't have this problem with other paints in their range (same thinning ratio) and I have had success with those by slowly building the coat up and achieving a perfectly smooth finish. I assume the clear is designed to be sprayed on as a stand alone coat unlike the Flat Base which I'm aware is to be mixed with other colours to flatten them. I'm obviously doing something wrong or missing something here so has anyone else had similar experience? Any help greatly appreciated. Also a big THANKS to all the guys who recommended the Iwata HP-CS eclipse when I was looking to buy, as this brush is making my paint jobs turn out better than I deserve with my limited experience.