Hi Chris,
I personally use a TT21 for ADSB Out, but mine was set up before I got involved with PilotAware and uses a different GPS driver. I have, however, helped a couple of others set up TT21s driven by PAW. It is quite easy once you get the right wires in the right places in the Trig Connectors.
One point I did notice is that you say 'I have the PAW Usb set to auto.' That is incorrect. You need to determine which port you have the USB/RS232 lead connected to and set that Port in the PAW [Configure] Screen to 'Transponder Trig'.
Looking at the PAW unit with the Ethernet Port on the Left, the USB Ports are numbered - top left (Port 1), bottom left (Port 2), top right (Port 3), bottom right (Port 4), NOT as per the PAW 'Quick Start' assembly leaflet, which is only designed to assist with plugging the unit together initially.
You also need to set up your TT21 as per the Trig Manual - if you have any problems come back and I will look mine up and 'talk' you through it.
Regards
Peter