I'm using Sonar Plat and just got a Roland A-300 Pro keyboard.  The reason I got it is because it's plug and play and I'm no MIDI expert by any stretch.  I want to be able to use it for some drum programming, keyboards, etc...
 
It seemed to PnP just fine - the knobs/faders work with channels/panning, etc...  I inserted Superior Drummer and was able to use the keyboard to trigger the drums.  I inserted the Waves Electric88...that worked too...as well as the Heartbeat synth that comes with Sonar.  However, I installed my Garritan Steinway piano and a VB3 organ and while the synth track is created...when i click on that track...nothing plays.
 
Interestingly, some seem to show 'none' in the input source for the track while others say 'omni' even though when you click the drop down the checkbox is on 'none'.
 
I'm not sure what to do here - this seemed pretty straightfoward from the start then i started adding a few other synths and they won't play.  I've tried selecting various options from the inputs and nothing seems to work.
 
What kind of things can you do to troubleshoot this?  In my preferences-> devices I only have the A-PRO selected (I don't have a midi cable connected from my controller to the interface...just USB).  I walked through the process I saw on a Youtube video of how to add the A-PRO as a control device so that part seems to working OK.
 
Just confused how a couple of my synth VST's fire right up and the others don't seem to want to do anything??

Hi. In the MIDI input drop-down menu, choose your A300 as input. I do not know why they behave differently.
All the best.

The "omni/none" thing is something lots of us have been saying needs changing for years. It's confusing at best, and can once in a while throw you a surprise if you forget to set a MIDI track input and channel correctly.
 
As Zargg says, check the A300 is selected as the MIDI track input port - this is additional to the settings in preferences/devices which simply tell Sonar which MIDI devices it is to regard as available.
 
If the A300 is already selected, it might be worth checking the VST is being sent MIDI on the channel it is expecting. Not all things work using the omni setting and need a specific channel selecting. Putting synths on different channels is often a good idea anyway as it helps prevent MIDI mis-routing and resulting chaos.

I personally use the A300-pro editor to set up a pre-set just for Sonar and define the midi channels and controls that way and then upload pre-set to the device and it works fine.

Apologies for last post that should have come from me as I logged in by mistake to my friend's account who I am helping to set up Sonar via Remote Access as I have introduced him to Sonar (perhaps I deserve a commission?)..

If you would like I can upload my pre-set to my dropbox if it helps as a guide?

Okay I am having one of those days mine is a A500-Pro so it might not help but I do have readable mapping xls sheet that I create by running a macro against the html data. Time I had a cup of coffee I think.