Problem assigning multiple MIDI channels to one instrument

I have a simple problem which doesn't seem simple to solve.

I'm running Sonar 4.03 with an Edirol UA-25 D/A and MIDI interface. I have a gorgeous brand new Roland Fantom X8 and my problem is that I can't seem to get more than one MIDI channel to connect to my instrument simultaneously. I've imported an .ins instrument definition file and I have MIDI data that I've copied to a new track. All I want for now is to hear two separate patches play the same MIDI data on two different tracks. The manual says I can assign multiple channels to my instrument and play different patches at the same time assuming my device is a multi-timbral instrument ( which I'm assuming a brand new, flagship Roland syth would be ). Every time I go back to my instrument settings it's defaulted to one channel - I've checked the 'save for future sessions' checkbox and when I mute one track I get the correct voice playing on the other so my assignments seem right - I just can't seem to route more than one channel to the instrument at the same time. What am I doing wrong? I'm pretty new to this as you might suspect. Thanks to anyone who can help me with what is obviously a newbie stumbling block.

Roland synths use a specific sysex message to assign two parts to the same channel. You accomplish this with a sysex that causes a single channel to address two parts AFTER you assign a distinct patch tp both parts. Roland thinks of parts and MIDI channels as divorceable and remapable.

Thanks... I will dig into the sysex messages to see if I can switch to performance mode or do whatever extra stuff that's needed to talk to my synth.

I thought it might be something like that... but the basic manual seems to make it sound easy. The only other reason I was confused was that it seemed like Cakewalk itself was not wanting to assign multiple channels. I had assumed that if it was the synth it might not work but the software would at least show that it was assigning multiple channels.