questions about .... electric drum kits and SD3 and SI

could use some help... sonar x1 producer - i am trying to record drums using an electric drum kit (yamaha dtx extreme ii - http://usa.yamaha.com/products/musical-instruments/drums/el-drumkit/dtxtreme/dtxtreme_iis/?mode=model) i have set them up via USB through SD3 and Si which everything works fine other than the kick. i have no sound when triggering the kick pad. it does show levels in the midi level meter but no levels in the audio level meter. any suggestion would be greatly appreciated.