Color Cartridges will not come out.

When I open the door of my HP Color LaserJet 2600n to remove the color ink cartridges they will release slightly on the left-hand side of the printer, but will not come out fully. The right-hand side of the cartridges will not release at all. Something is locking (holding) them in place from coming out or releasing them. What should I do? Do you have something on how to take them out?