Why won't my wii controllers work?

Is the sensor bar connected properly?

Are you syncing them properly? Near the disc slot there's a little white flap. Open that and hold the red button down while holding down the small red button on the Wiimote (under the battery case) until the 4 lights at the bottom of the Wiimote stop flashing and one remains lit. You may need to try a few times. Don't stand too close, either - about a metre or 2 away.