Bradle95,
The card may very well be in the wrong input mode. The correct mode for the way your signal is wired is Referenced Signal Ended, and the default mode for the card when you install it is Differential.
To change this, go into Measurement and Automation Explorer (MAX), expand the Devices and Interfaces Folder, then expand the [Traditional] NI-DAQ Devices folder. Right-click on PCI-6025E entry and select Properties. Go to the AI tab of the properties window, and on the Mode dropdown menu select Referenced Single Ended.
This will make the board read the signal between the AI channel and AIGND, which is the way you have it wired.
RossC