Removing front license plate

How do you remove the front license plate holder on the '97 Civic? If you take of the front bumper, you see 2 bolts on a long (staaf met schroefdraad, don't know how to tell it in English) rod. I tried turning them, and they rotate, but they don't seem to be doing anything. The license plate holder doesn't move:confused:

So does anyone know the tric?