Normally the parts under the chrome are the same color plastic as the kit, not always, but most times.

The parts could have a clear coat placed on the parts, between the plastic and the chrome coating, but this shouldn't affect a primer coat.

Did you use pure bleach? Or some thing that is a solution with bleach in it? Take and run your parts in warm water with a bit of dish soap, and gently scrub the parts with an old toothbrush, there could be a build up of something on the parts from the bleaching process that is preventing the primer to stick.

I am assuming you are using an acrylic primer?