explorer5.0

I am trying to tune my truck this weekend and I am having trouble datalogging my wideband to the analog input of my Xcal 2. When I put my voltmeter to the output of the wideband I get a steady 2.6V at idle, which equals 15.4 AFR, but the analog input reads all crazy. I get a wave pattern that ranges from 10-20AFR(averages out to be correct), and I know my formula is correct. If I run the Xcal without the formula, I see the bare input voltage fluctuating. But when I put a AA battery on the analog input I see a constant 1.5v, which makes a constant 13AFR show on the log. What could be causing the fluctuation on my input? I have tried running a ground straight to the battery, and making a new analog input wire but I get the same results no matter what. This is an AEM UEGO wideband BTW. Any info would be appreciated.