Check your connections to the light. If you have a VOM Meter;
1) Place it on the "volts" setting and read the voltage between the two posts that the lamp hooks up to, record voltage.
2) Then go between one post and a known good ground point and then the other post, recording voltage as you go. One should read zero volts, as the other should read higher or close to the voltage from step 1.
3) If voltage is the higher, you have a high ground resistance; if the voltage is close to being the same you have a high resistance in the positive line. You can try this with and without the lamps "burning".
I was a Shade Tree Mechanic, but had to cut down the Shade Tree to make room for the garage. Does this make me a Mechanic now?