Halide Lighting Won't Fire

I just bought a dual 400w metal halide lighting system. In the store
the fired it up before I left, they did have problems getting it to
fire but blamed it on the circuit they plugged it in to. Once home I
mounted them to the top of my canopy and tried to fire them up, it
took a little fiddling with the plug into the transformer and turning
one of them off so the other could fire, but now that my canopy is
back on top of my tank I can not get them to fire up at all. Could
the bulbs be bad/broken now?!! I checked the voltage at the bulb and
the transformer and it read 272 volts, when I take my voltage sensor
there is power inside of the bulbs. Any ideas or suggestion would be
very helpful as these bulbs are about $150 a piece. Thanks.