That screenshot is telling you what the issue is - the codec is in standby mode, aka "asleep" or "not awake". This is normal, the default time is for the codec to go into standby after ten minutes of non use - if nobody changed it on this system that's what it's doing. You need to click on the screen to wake it up, and then remote monitoring will work. If you are clicking and it's not waking up, try placing a call, but I'm guessing that will do it.
