I'm borrowing my friends night goggles dvr. It's new on the box. I am hooking it up to my pulsar apex and playing around with it until I get one myself. It record great but I can't seem get audio to record with it. I'm using the double cable for an external battery for the thermal and an rca for video. Tge cable I have hooked to the dvr is the one that came with the night googles pkg (3 way rca to the thermal and Walkman type to the dvr). Is this the right cable? Maybe I have it hooked up wrong? It records nice but no audio.