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AD8606 - inverting amplifier not working

Hi, 

I am using both the Opamps of AD8606ARZ. One is configured as non-inverting unity gain amplifier, while the other is inverting amplifier. However the output is not as expected - not even in LTSpice simulation. Can you please check what wrong I am doing here? 

Basically, the circuit is the same from the ref. design of AD5933 - CN0217-DesignSupport. Why are there two 20K resistors in that circuit? Attaches its schematics here. I do not understand how the Rfb - which is a feedback resistor to AD8606 part B, is accounted for the feedback resistor for AD5933?

 EVAL-AD5933EBZ-SCH-RevC1.pdf

Regards

Rahul