M System Linearizer JFX-66-R

Does anyone have any knowledge of the M System signal conditioner? It has a 1-5V dc input and 1-5V DC output. I am currently trying to generate a function using 4 points for the input and 4 points for the output. When I attached the linearizer to the laptop via the JX configurator kit loaded the software on and inserted all the data into the correct spaces I believe. Choose the correct model, set the correct input range, set the scale of the 0% input value and the 100% input value. Then I came across the fine zero adjustment and the fine span adjustment. I set the zero at 0% and the span at 100% for this test. I then plugged the 4 points into the linearizer section in the X and Y columns and downloaded all of the settings as a cfg into it.

Currently the little black box is attached to a 24v power supply. I have been trying to simulate the input voltage with a fluke 744 sending in 1 to 5 volts and testing the output with another 744. But heres where the problem begins. If i input in 1V I get a voltage on the output close to what im looking for, I try 2V's and get another number a little larger then the voltage im looking for but after 2V's my voltage doesnt increase anymore. 2,3,4,5V's all give me the same output voltage. Does anyone know why I cant get the output voltages correct? I tried the I/O check section in the JXCON program to simulate an output, and if i put in any percentage from 0-100% the output voltage comes out correct exactly what im looking for.

So after reading this essay...why does the voltage output come out correct on the simulation but not when the input voltage is added?

Thanks.