Radiator wont release colant

i have a 1991 cavalier 200,600 miles and i replaced the thermost along with coolant and cap, and now the radiator wont relase the coolant back into the resivoir and wont take coolant from it!!! is there differnt types of radiator caps and i grabed the wrong one? any help would be apreciated thanks.

Did you fill the radiator? The exchange of coolant between the tank and the radiator relies on the expansion and contraction of the coolant due to heating of the engine. I hope this puts your mind at ease. Fill the radiator and it will level out over a couple of heating/cooling cycles.