Issues setting up a pH / Conductivity Current Transmitter

Hey guys, I purchased a CDE-300 dual pH/Conductivity 4-20mA transmitter and I'm trying to test it out via reading the output with a scope (unfortunately I don't have a current meter on hand). The manual is here: http://www.omega.com/manuals/manualpdf/M3872.pdf

Basically, this thing is powered with a 12VDC psu and there are two connections for pH and conductivity. The manual says (2nd Page, OUTPUTS headline) that the outputs are not powered and so must be connected to the 12vdc supply. Basically, S1 is connected to your sensor, and the ground of your sensor is connected to +12Vdc, the 0 connection is tied with the 12vdc ground.

In order to measure this on my scope I connected a resistor from S1 to the +12VDC and tied 0 to 12vdc ground. I then connected the scope to the S1 side of the resistor and the scope ground to the 12VDC side. However I get no output voltage...

I'm wondering if I hooked it up correctly or if it is indeed working. Note I'm using a USB scope (Digilent EEBoard) so I duno if that changes things.

Here is a picture of how the manual specs the connection and below that is how I hooked up my scope. http://i.imgur.com/o4I0j.png

Thanks