Computer Connect??? on 2005 Buick Rainier

We took our Rainier to Auto Zone to have it hooked up to the computer to be scanned for any engine problems among other things but, the computer could not read my vehicle and could not connect. The employee at Auto Zone said something had to be unhooked in order for the computer to not pick up and scan my vehicle. Does anyone know what this could be or how to fix this?

Asked by for the 2005 Buick Rainier
I would have tried a second scanner for this. May have been their scanner and not your car. If has been recently worked on in the dash area then yes something could be amiss. May also be just a wire connection at the connector under the dash. Some digging is required.
I honestly don't believe anything was wrong with the auto zone equipment because they hooked the scanner up to my dad's truck after trying it on our's when it didn't work and it picked up my dad's truck with no problem. Do you know of anything else we should be looking for under the dash if there aren't any disconnected wires?