I have Sonar Platinum but I need a serial number for TH3 to use it.  Does anyone have any idea how I can get the serial number for TH3?  I tried using my Sonar Platinum serial number but that doesn't work.
 
Thanks,

TH3 Cakewalk does not require activation. It is a lite version of TH3. TH3 Cakewalk includes the full version of TH3 which does require activation but that is a separate purchase.

Thanks for your response.  I have the plugin loaded in my guitar track, but no selection I make in TH3 makes any difference in the sound processing of my guitar as I play notes.  Do you have any thoughts about why this is happenning or what I need to do to actually use TH3 as a sound processor?
 
Thanks for your help.

Unless the track is already recorded, input echo must be enabled on the track to hear plug-ins. This will have the side effect of delaying the signal you hear. The amount of delay depends on the buffer settings in Preferences > Audio > Driver Settings Mixing Latency section or ASIO software.

Do you have Input Echo enabled? It’s required to hear incoming audio being processed by an fx in your case.

If you're using TH3 Cakewalk, not all of the presets are activated. Try banks 24 and 25 for starters. That might be your problem. Or maybe not...