Cant replace audio in vid file

Hi. Using W7 Ult 64 bit. Have the 64-bit vers of Cubase7 installed, and QT as well (not pro).

I have an mov file with the MPEG-4 codec, and it has no audio. It imports into Cubase and plays with no issue.

I am trying to perform a replace audio in vid file, but I cant seem to get it to work. I see the Cubase progress bar, and in the directory where the vid lives, another .mov gets created temporarily - just like it should. But the end result is a vid file with no audio.

Have tried wav, aif, mp3. Any ideas?

Thanks in advance.