I too have this issue (for years) with both Rapture Sessions and Rapture Pro. Both are in Demo mode and I've tried offline activation but it doesn't work. I've tried turning off the firewall, I've tried reinstalling through CCC, as well as, direct download and install in hopes I'd get a pop-up window which would allow me to manually input my serial number and activation code, but so far no luck.
I've been trying to reach Noel, or someone from Cakewalk for help with this. Robert, who did you contact that helped you?