Krell HTS 2 can't find audio signal

I have a new Krell HTS 2 decoder which works fine for DVD applications but can't seem to find the signal from my Time Warner Pioneer HDTV receiver. If a program is playing in 5.1 I'm okay, but if I switch to the next channel which is in 2.0 the Krell just clicks(and keeps on clicking)but won't pick it up. If I continue for another couple of 2.0 channels, it will finally pick up amd then play all 2.0 channels. Going back to the 5.0 though now creates the problem. It doesn't change the audio format without alot of hand wringing I'm forever clicking back and forth to gert signal. I've already changed the Pioneer box once, but to no avail.
Anyone, anyone?
By the way does anyone know of an HD box I could purchase that would be compatible with Time Warner cable in NYC?