Yellow … flakes?

As promised, the next layer of colour on the tanks. Its Vallejo RAL Dunkelgelb as Surface Primer. You could spray it right onto the tank, but i prefer doing it on top of a primer.

As i got to the third tank, a big disappointment came along. The primer on the Kingtiger chipped of in flakes by the air pressure of the airbrush. First thought was a simply wtf?

Now the big question, how to proceed? Do i strip the whole thing? How do i make sure it doesn't happen again? I washed it like you should with warm soap-water and used a proper primer, i use for several other projects without any problems (HIT Color Belton and Army Painter).