I am trying to perform conditional formatting on a cell to highlight when there is a mismatch in the cells

Cells in col b have values like US123 or CA456...cells in col d have values like us456 or ca789

Using the formula =MATCH("*"&LEFT(B10,2)&"*",D10,0) gives me the exact opposite of what I am looking for. This formula will highlight a cell in col d that starts with "us" where its sister cell (in col b) also starts with "us". What I want to do, is highlight col d if the first two characters in each cell do NOT match.

I have tried =not(MATCH("*"&LEFT(B10,2)&"*",D10,0))...but basically nothing happens...no error...but no highlighting. I've been searching and can't find a "nomatch" type command, or a variable for match that would return something if cells don't match.

Any insight would be appreciated.

Thanks,
Bill