Lab12 DAC1 Reference Problem

Guys, got this DAC a few days back, and having a problem connecting it to my Electrocompaniet ecm1 UP cd player via rca digital out. The signal is not stable, goes on and off. The Bluesound streamer works fine with it. Connecting cable is Nordost Silver Shadow. Already talked to the dealer, while he didn’t know the answer he offered either to replace it or refund my money. Going to return it, but I really like its sound.

 What could be the cause of this glitch? Ideas?

Thanks.