The first generation of Peer-to-Peer DVR units and NVR units were only compatible with HDMI TVs that support 50Hz variables.

HDMI TVs will support either 50Hz, 60Hz, or both variables.  The Hz specification on an HDMI TV indicates the unit is frequency in which the device (DVR or NVR) communicates a video signal to the TV.

If you connect your DVR or NVR to an HDMI TV and you do not see any video signal on your HDMI TV, then most likely the issue is that you are using one of the devices that only supports 50Hz HDMI TVs and your HDMI TV only supports 60Hz.

A resolution for this is to use a VGA cable to connect your DVR or NVR to your TV.  All DVRs and NVRs support VGA video.  Additionally, the only devices that are not compatible with 60Hz HDMI TVs are video resolution 720P or lower.  Therefore, the video resolution on on these devices will look exactly the same regardless of whether they are connected using HDMI or VGA.