OSX El Capitan, CUBASE 6 and Behringer UMC204

HI. With the band we bought Benhringer UMC204 USB2 audio card, which we planned to use for playback samples from CUBASE 6 on stage. Cubase is installed on Mac OSX El Capitan. However immediately after Cubase starts, audio card has overloaded inputs without any connected inputs. This creates an incredible sound and the card is unusable. But same card on the same computer works with no problem in Garageband. Can anyone help me with this issue?