I have having an issue in Cubase AI 4, I did a screen capture video of the issue, it’s on youtube here: - YouTube
Running a Mac Pro on 10.7.5, with a Behinger U-Phoria UMC404HD through Cubase. The interface is recognized by the computer as well as Cubase, but I have no input signal, likewise no output signal.
I am fully able to record audio in Garageband with the same interface (also, the audio for this video was recorded with it).
1st post. Welcome. 
A few thoughts to start…
What I don’t see in the vid is the audio track inspector section showing the assigned input and output.
So…
Did you assign a Behinger mono input and stereo output to the audio track? It can be done in the inspector.
Also, in the devices menu find the option to show the mixer. You really want that to adjust things.
Looks like there is an automation “read” function enabled. Don’t confuse this with the track “record enable” function.
Remember… you must enable the track “record enable” function to record on the track. You also need to enable the track “monitor” function to hear while recording. Turn off those two functions to hear what you recorded.
Regards. 