I had an electrician install some overhead lighting boxes in a few rooms in my house, and yesterday I bought a new chandelier to install over our dining room table. The electrician installed what appears to be a blue Carlon 4" box. The chandelier includes a mounting bracket and two machine screws for me to attach the bracket to the ceiling box, but I can't seem to get the machine screws to screw in all the way. The box is a deep set model, and the screws are only about an inch long, so there is no way they are bottoming out. What could be going on here? I would assume that all of these ceiling boxes all accept the same size screws, and that the chandelier would ship with this size screws but it doesn't appear to be true. Do I need different screws for this type of plastic ceiling box? Any suggestions?