Doing a small remodel of a bathroom, the original finish was stipple on the walls. To get rid of that I first sanded them (probably 3-4 coats of oil base semi gloss), washed with TSP and then skimmed it with texture mud. A light sanding and 1 coat of Behr drywall primer and sealer. When I applied Kelly Moore interior eggshell latex enamel today, it raised a few small blisters in two different places. Is this because of the oil base underneath or insufficient primer, or ??