Photoetch is tricky stuff. I FEEL YOUR PAIN
After cleaning in acetone, I prime mine with Tamiya's paint. Gray or Panzer yellow, and then assemble.
Make sure your folds are clean and of the correct angle, sometimes pressure from the PE trying to spring back with undo the CA hold.
Third, I use a fast drying, gap filling CA. I have never had problem with it holding the PE together.
I know the kit of which is giving you fits... It is tough, but have patience and it will turn out.