The INA128 is a differential input instrumentation amplifier. It is designed to amplify a small voltage difference applied to pins 2 and 3. It is not designed to act as a "current amplifier" for a current injected into one of the inputs.
The photo diode should be connected cathode to +12V, anode to a resistor the other end of which is grounded. Connect pin 2 of the INA to the anode of the photodiode.
This way, the reverse leakage of the photodiode is modulated by incident light, and this current creates a small voltage across the resistor. This small voltage is amplified by the INA.