Have you got the install instructions? I never seen a tstat that needed a ground

Yes I have the instructions, it does not specify which terminal is used for the common. (c)

OK,, common,that's not a ground,, can you tell us the lables on/beside each post of the WR tstat

I have r,y,g,e,o,b,L,x1,w2

What does the instruction sheet tell you the b post is used for?
Some tstats don`t need or call for a common post,the common post is mostly used to return the low voltage (24V) back to circuit board so as there will be no need to use or worry about changing batteries

B is for the reversing valve if energizing in heat.

O is for the reversing valve if energized in cool