No Audio From Line Inputs

I have a UR22. I get computer audio from it (Youtube, iTunes, etc.) but no audio from the line inputs. I am using Cakewalk Sonar X3. I have Input 1 of the UR22 set as my input source for the Audio track. I have a Korg Volca Bass synth connected to Input 1 of the UR22. Even with all volume/gain levels maxed I get no reading on the meters of the audio track. Tried plugging a couple iOS devices into the UR22 to see if it would be any different. No audio from those either. Any ideas?