Epoxy resin hotcoat beads up??

Hi everyone. I need a little advice on using epoxy resin. I just bought a used board, and it has a couple of spots where it feels like the glass was squeeged too much and the glass texture is exposed. It does not leak, but I figured I would just paint on a thin coat of epoxy resin (board is epoxy Point Blanks). My resin keeps “beading” up. I lay it thin and smooth with a foam brush and it looks great but then I go back in 10 minutes and the resin has beaded up almost like water on a waxed car? What did I do wrong? I think the underlying layer was sanded to at least 280 grit. Is that too smoth for the epoxy to stick to? I would’nt be surprised at adhesion problems, but cause beading. I don’t think there was any wax left on the surface. I cleaned it well with acetone. Am I using cheap resin? I only needed a little bit so I bought one of the popular “Ding Kits” for epoxy. I’ve tried twice now with the same results. Any advice would be appreciated. Jeff