I'm reviving this thread to see if the OP got this fixed (or if anyone has any further suggestions). I'm having the exact same problem. Seems like only one way communication (although when I move the fader there is output midi communication). This is on a new install of X2a Prod x64. on new hardware (Win7 Pro x64). I have tried most of the "tricks" to get it installed that I have found on the net with no progress. I know this product and drivers are not made/supported any longer but would really like to try to get this to work and I know some folks here have gotten it to work.
 
Gigabyte GA-Z77X-DH3, Intel i7-3770 3.4, 8GB RAM, Windows 7 Pro sp1 x64, Sonar X2A Producer 64-bit, Fireface 800
 
Thanks -Jim  

It's working ok.
 
You can check to see if it's working (sending) by opening it using the midi Midi-OX tool. You an Google Midi-OX to download the tool. Also, make sure that the Alphatrack driver is set to normal.

Thanks SuperG I did see that on another post and it is sending. Can you explain how to check if the driver is set to normal I'm not sure how to do that. Does it have to do with the AlphaTrack.dll?

Yes. Click on the Alphatrack icon on the notifications area of the Windows taskbar. If it's not showing, right-click to bring up the windows notification dialog.