UR RT2 info

I was trying to use the RT2 to make a recording of audio from a DVR using the sound output on the tv and going in the line in 3-4 on the back of
the RT2. I was using Apple Quicktime. It saw the RT2 and it was selected but there was no audio coming thru.Not the usual purpose for this
device but I thought it should work. The audio was analog and I have been able to capture audio on other computers…
any idea why it wouldnt work?