LoadCell and INA122 problem

[Yaro]

I have a problem using an instrumentation amplifier(INA122), here's datasheet:

ina122.pdf

I've used the scheme in page 9 figure 5. Is powered by +5volt from arduino diecimila.
The bridge have 4 resistors of 350ohm (3 potenziometers and 1 strain gauge)(result Ro is 350ohm on Vin+-) powered too by +5volt from arduino. The problem is that the output is 0v on Vout, so amplifier does not amplify my input imbalance when i change pression on strain gauge. I've tryed to change Rg but nothing, the output is always 0v. All connections are right and without short circuits.
I have on Vin+ and Vin- 2.3 milliVolt (due to the imprecision) and 3 milliVolt on output, and the output don't change if i change the voltage on Vin(i've tyed within +-0.3 milliVolt).
What i'm doing wrong?

[MarkT]

Bit more information would be good, such as a circuit diagram with all the values marked. What voltage are you feeding to pin 5, the ref pin? If the bridge isn't balanced the output could just be saturating (less likely if you select low gain and set the ref pin to something above 0V.)