Flat surface treatment problem 'again'

Hi, ladies and gentlemen. I truly hate to bother you folks with the same question again and again. But I am STILL stuck with the same old problem. Some of you may have recalled that I used to have problem about white residue on my Mr. Color clear flat paint. Now I am using MicroScale Micro Flat finishing paint. The white residue is gone BUT the flatness of the paint is not strong enough to cover the gloss clear paint that I used to seal the decal. Now I am having a semi gloss Revell/German Luchs. It's all right to have this on an a/c but not on an armour car!! I re-spray few more times without success. Now my questions are:

1) Did I do something wrong in the thinning part? I use 1:1/2 of paint and alcohol.

2) I once used enamel clear flat(from Humbrol) by brush and that work great except it remained brush marks. So is enamel flat clear is always effective than acrylic flat clear?

3) I wonder what flat finish paint you use. Is the Testors enamel flate clear spray work fine?

Thanks for all the help