Electrical problems are either easy to solve, or a mess to troubleshoot. I would run a ground wire to the chassis grounding point (you didn't make it clear if you ran a separate ground, the mounting point for the lights might not be a good ground). Also, I do hope you made sure you have a fused hot wire, and not connected directly to the battery. Many a burned up mess evolves when people jury-rig wires to a 550-800 amp battery directly. Finally, if all your connections are of a high reliability (soldered and securely insulated) I would suggest a bad switch or a defective lamp assembly. In closing, many wires in modern cars may have 12v (as a rule they of course vary with battery voltage and system load, and vehicle running or not) that are subsystems or signal voltages associated with the various systems in a vehicle. Gone are the days when people could use a 'tap-a-line' on a hot lead under the dash. You have to go to a confirmed hot/light positive lead to 'source' a supply for the (if relay fed) power lead, or a switched hot lead if the current is available. Good luck!