I have an apartment building with a photosensor that controls two light fixtures and 4 entry lights. Since I bought the place the end of the line light post has not worked. I replaced all of the lamp post heads as they were all missing glass, and figured this would solve the problem. However, it is still not working. I took it all apart again, stripped the wires back about an inch and reconnected everything in the two lamp posts (the end of the line one feeds from the other). The light still does not work. I have a field tester and it tests hot, and the cfl inside has some dim flickering near the base. Aluminum wire feeds into the first post, with copper coming out. I made sure the connections were tight yet again and still no luck. It looks like someone else has tried everything I did because the wires were short (I had to cut back insulation) and there was white residue on the wires(I forget the name but know it is for this purpose). Any ideas? Thanks!

The underground cable may have a break in it. Need to use a voltage meter to check where the voltage stops, and then use an ohm meter to check continuity of the cable that does not allow the voltage to pass.

... and also using something a little more accurate than a field tester to give you an actual reading of the voltage level would be helpful...