Ag/Pt electrochemical cell

Does anyone here have any experience building circuitry for electrochemical cells? I've got a rather expansive problem with my circuit, or more appropriately, a series of IC's I've been using.

Basically, I'm sensing current across a load resistor using a current sense amplifier (MAX4377 from maxim-ic.com). When this IC (or any IC for that matter) is sensing current, or a differential voltage, I get bizarre, static voltages across the differential inputs and almost a maxed out voltage at the output.

The circuit is pretty basic, but I want to make sure someone has some experience with electrochemical cells (specifically an oxygen-sensing Clark electrode) before I go through putting up circuit diagrams and such.