Ritetemp Thermostat Manual

I installed new thermostat ritetemp 6022. Mine wiring 7 son. Matched all son, except 'X'. After referring to the manual I found that "X" means "C". Thus, every son are paired as below:
W W
O O
Y Y
G G
R R
B to B
and
X C

air conditioning and fan works properly. But the heat did not work.
I see the note in the manual ritetemp 6022 saying: "If there are two son B and O, DO NOT connect to terminal B B B Connect to terminal C '.
If I connect to the BC terminal would I do with the thread of X, I connected to C. Should I ignore this thread.
Before making this chnage need some expert advice.

There should be an 800 number for assistance in the installation manual. Call them and they will help her.