@largecamel: Does it heat up at all? Did you insulate it? is there a fan blowing at it? is the thermistor hooked up to the right input?
@ElectroTurk: sounds like your thermistor is hooked up correctly. With the power off, disconnect the heater wires and measure the resistance with a multimeter. it should read ~5-6 ohms. connect the wires back up and power it up, switch the multimeter to volts and test for 12V across those same wires. (make sure you don't short anything out with the probes, wrap them with electrical tape)