I am working on a 2007 911 (997) and I am able to connect to the TCM and read all the date. The only issue I am having right now is the software update to code the TCM. And I don't see the option on the tablet to program it. Apparently you can use your laptop to load the software through the J2534 unit.
If you have electrical connection issues to the TCM then you may not be able to read the data from it. Check the codes on the ECM and the CAN units to see if they have any codes that say "Software incompatibility with transmission control unit".