strobe hide a way’s in '08 chevy hhr

Last week I installed a set of Whelen DOT-66 strobe hide-a-ways in my 08' Chevy HHR. I mounted the power supply directly to the frame in an enclosed area and mounted the strobes. When I connect the power and ground directly to my moped battery they work great! However when I wire them up to a ground on the frame and to either the remote positive post in the engine compartment and/or directly to the positive post of the battery they barley even flicker...not sure what could be causing this and has dumbfounded everyone I've asked. Any idea on what could be causing this or where to start? Thanks

Best guess would be that you are not getting a good ground. Be sure that the surface is bare metal and free of any wax or paint.Brad Marvin

That's what we thought, but it's not. I've tried running both the positive and negative straight back to the battery with the same result. If I take those exact same two wires and connect them to my moped battery they fire right up. Ive been working with Whelen as well, but they are also boggled. Called the dealership and spoke with a mechanic and he said there is nothing special about the 12 volt system...I have no clue....

Okay, so the questions grow... I disconnected the battery from the car and ran the two wires to the battery and the strobes fire perfectly...so why when the car is connected to the battery doesn't it work? The strobes do not tap into the vehicles system anywhere else but those two wires...

Appears one of the strobes has a short...gonna try and pull it out and hopefully replace it over the weekend...finally some things are starting to make sense...