Track gain issue.

I have 3 audio tracks, 2 are audio inputs on my Focusrite interface and the 3rd is USB audio input from a Virus Snow.

Track gain on the Virus track works and adjusts the incoming volume but track gain on the other 2 tracks has no effect at all.

I was sending all the tracks to buses and using gain on the bus but thought this might be a waste of resources, why not just do it at the track level?...until I had this issue.

Volume fader has the expected effect just not the track gain.

Any ideas why track gain is only working on the Virus track?

As Bruce said, If your talking about setting recording levels, that has to be done at your interface, Sonars track controls only affect the playback not the recording. 
And the gain control most certainly works on playback.