I was demonstrating the TW-12C and some RTS and CC kit and how it interfaces the two. We had the CC kit on System 1, and the RTS on system 2.  The system only talked if the 2/3CC switch was to the left (for CC and RTS).  The other switch was set left for CC and right for RTS.
Answer: on some TW-12C units the switch settings silk screen do not match the manual
The most important thing is the silk screen setting for the "2/3 C-C". Double check the screen printing the front of the unit , it may not match the screen print on the rear or the manual however ALL are in agreement. The settings are ALL the same , just the ordering is swapped around