take your bulb out, hold it up to some light and see if the contacts that hold the actual lamp in place are in tact. the one we had did this a couple times, coudn't figure it out then took out the bulb, held it up to the light, and you could see one of the contacts on the bulb popped right off of the element inside the housing. you will play heck arguing with Richmond to warrantee that, if that's the issue. you may need to put a power condition between your power source and the unit, these units are very very sensitive to voltage issues.