1. In multi window the output is blank. Check if the sub stream of the camera has been enabled or not (Main Menu->Storage->Record). Solution: substream recording was not setup.
2. If the multi window output is blank, then check the sub stream type of the camera is H.264 or not (Main Menu->Remote Device->Encode). Solution: the encoding stream was setup incorrectly.
3. If the multi window output is blank, then check if the device supports camera sub stream resolution or not (such as 960H, D1, HD1 and etc.). Solution: Find compatible hardware.