When you trouble shoot anything start in the middle and work towards either side. In this case the 1st action should be pluging the light into another power source. If it lights up then the problem lies in the
dimmer. If not it is in the light.
Now you can trace it back another step. If the fixture does not light up try a new lamp or continuity check the lamp if the lamp fails its the lamp- it it passes then the problem lies in the wiring.
If the light worked when it was plugged into another source and the issue is the dimmer pack, plug something straight into the pack- no extensions if it works then the problem is the cable. if not it is the dimmer for sure.
My gut is telling me to meter the power coming out of the dimmer pack. I have a feeling that if it a lesser quality pack off might not be 0
volts and it might be 'leaking' some or preheating if that is an option. Enough to light up a tester but not enough to light up a lamp. If thats the case the problem lies in the addressing of the pack up the dimemr it self. I have seen chauvet (sp) packs with blown circuits do to over draw.