? Black Patch spots on the Trunk???

The only problem I had when painting was the right side of the trunk. The paint would wrinkle up in two spots. Apparently the paint was reacting to what was underneath in those two sections. So I sanded the sections down to bare metal, prep cleaned and sprayed it again. But the same wrinkling occurred. I sanded back down and prep cleaned the same sections again. Next, I taped off those two spots and used a sealer primer so I could install the trunk back on. I said to myself I would fix it later, but that never happened.