Help: MinimOSD works when camera is not powered but wont work when the camera is powered up?

My Micro MinimOSD is wired to the main battery for voltage monitoring. The PDB I am using has two voltage regulators (5v and 12v). The 5v powers my NAZE and microminimosd and the 12v powers the camera and video transmitter. The camera and video tx are both also connected to two of the ground points on the OSD It is rate for 3A. The OSD works and displays the voltage when the camera is not powered but wont work when the camera is powered up? Anyone have any ideas?