I think I'm having the same problem.
I washed/de-greased, sanded, wash/de-greased, etched with 50/50 white vinegar/water and dried well.
I spray primed with well mixed Duralux Zinc-Like primer M739 and dried for 24 hours.
I sprayed on two coats of well mixed Duralux Duck Boat Drab M691, 24...