sounds like you still have air in the system.
on a cool engine (after a drive, let it cool 30 mins), take off the radiator cap. make sure it's full.
Start the car, let it run until the tstat opens and temperature rises. Open the bleed screw on the tstat housing until you get a good stream of coolant the close the screw.
Top off the radiator again. keep an eye on the temperature, and repeat again if needed.
Finally put the radiator cap on, make sure the overflow bottle is filled, shut off the car.
