I have a similar problem with a client (just the one) and have been told that it is probably due to her having a very oily nail bed. It does not seem to dehydrate no matter what I do to it. I have now been advised to use acetone to prep the nail, but I don't see how this will work because there was no difference after having a complete soak off and new set - when the nail bed should by rights be totally dehydrated! Just out of interest, which monomer has the strongest adherence? I am currently using IBD "Grip" monomer and "Flex" powders which came with my college kit, but are there any products out there specifically designed for nails which have poor adherence?