Is the backplane actually hooked to that thingamajig that turns it into an Amphenol connector? I know it has a name. Maybe if that cable is off or not seated or however that thing connects to the backplane that could be the problem? I know V7 has those adapter things - don't know for sure if V6 has them too because we skipped over that version.
Just me speculating. That would be secondary to the power supply, of course, but I would assume if it was a power supply there might be other issues....