Thank you so much.
Will take this thing into account for the next time.
You cannot because of the G mismatch between PGA (if you tried using those)
or the Aol mismatch one OpAmp to another. Depends in latter case how much
CMRR you are willing to forego.
Here is a analysis - http://www.cypress.com/?app=forum&id=2492&rID=82151