My North Star DAC -not picking up Toslink from STB

Hi Folks:
I just bought a North Star Transport and DAC combo and am very happy with everything. However, with my old DAC I was able to easily connect my DirecTV STB tuner to my DAC (A Bidat) via toslink and get sound that way. With the North Star, somehow the DAC is not picking up that signal. More confusing still is that I tried another transport, and the Toslink is working fine there (DAC is picking up the signal). So, I'm guessing something may be awry with my DirecTV Toslink output? I do see a red light generated at the input end of the toslink cable, so signal is going from the DirecTV STB. Can anyone offer any potential remedy.? the Direct TV STB only has that one digital toslink output, so I can't avail of other outputs. Might there be some issue with the cable? Anyway, I'm hoping some of you would have suggestions on how to remedy this. Thanks in advance!
John.