Volume control midl problem Sonar

I am using a Kurzweil K2600XS keyboard.  I have set midi channel 1 with a bass, and a piano on midi channel 2.  I am going to record two midi tracks in Sonar.  I record track one, using midi channel 1.  I begin to record track two with midi channel 2.  But midi track two is way loud, so I turn it down to match midi track one.    Unfortunately, this also turns the volume of track one down. Volume levels have always been independent of each other with Sonar, on other keyboards.  I surmise it is the Kurzweil.   I have tried both the velocity and volume slider, to no avail. The problem is the volume for all 16 midi channels are somehow linked with each other in the Kurzweil, both during recording, and with playback.  Changing one volume slider in Sonar changes all the midi channel volumes in the Kurzweil, yet the other 15 sliders in Sonar do not move.  Is there a way to bypass this problem?
thanks,
wadrum