I need help with getting an AD8553 to work. Question: Referring to Figure 30 in the data sheet, I do not measure the voltage across R1 to be equal to (Vinp-Vinn). I also do not realize the gain as set by R1 and R2. My circcuit conditions: Vs=5V, Vref=2V, Gain 6. What is wrong? Help, please!