Please help!

I have pretty much completed the glassing of the wing with polyester resin but for some reason there are a few small spots that won't dry. It's as if the catylist has no effect in those areas because they are still sticky - and this is 2 days after the glassing. I tried a second and third coating over these small spots and no luck. I even tried brushing on a few drops of the catylist over the spots and still no luck. Does anyone know what causes this? Should I just sand away these spots and use a patch piece of new cloth?

Thanks for the help!
Chris