MIDI input garbled in Sonar X3E Producer

I'm experiencing a bizarre issue with Sonar X3e producer.  I've just installed a new MIDI interface, an EMU Xtab 1.  One in, one out, nothing fancy.  It's connected to a Fatar Studiologic 900 keyboard.  The keyboard works fine when connected to a standalone Roland JV1010.  When it's connected to Sonar via the Emu Xtab, all hell breaks loose.  Keystrokes generate random pitches and even arpeggios, and I can't seem to control which instrument receives the MIDI notes.  Anybody have any idea what is going on here?

So you have the keyboard's OUT connected to the interface's IN, and the interface's OUT connected to the JV1010, and that's it? Are you echoing input out to the JV1010 or to a soft synth in SONAR?
 
It shouldn't make any difference if the routing is as above and there are no MIDI-generating synths in the project, but you should make sure the MIDI track's Input is set to a specific channel of the one hardware MIDI IN as opposed to All Inputs - Omni which it will default to.