The 4 lights won't come on for the Wii-motes? To fix that, just unplug the Wii and plug it back in. Problem solved. Works for me every time. I get this problem at least once every 2-3 weeks.
For the Sensor bar, make sure you are about 4-10 feet away and make sure you are directly in front of it. Turn out any lights that may be interfering.