Hi Robbie,
Thank you for using ADI products on your circuits. What specific application are you doing? I am glad that you already make your circuit working. But I would like to take this opportunity to endorse our new tools for INAMP Design. Depending on your configuration and your circuit requirement i.e. differential input voltage, common mode voltage, suppy voltage and gain, this tool will show you if the part is operating within its range or not. You can view here the common mode voltage vs output voltage plots of the device which shows the operating region of the parts. It also has a tab for recommending alternative inamps product in case your current inamp doesn't fits to your requirement. It would be very helpful for you to use this tool nextime to avoid this kind of trouble.
Here is the link: Instrumentation Amplifier Tool - Common Mode vs. Output Voltage (Diamond Plot)
I would appreciate if you could also give us any feedback regarding this tool.
Thanks,
Emman