The oil gauge in my 2007 Silverado (new body) stop works

Hello I just install the Diablo tune in my 2007 Silverado and the oil gauge stops to work. Here is what I do:

1.- Plug the Diablo tuner into the truck port
2.- Run a diagnostic and erase some codes
3.- Install the Diablo tune, the tool automatically back up my stock settings, then the diablo tune was installed successfully.

After installation the tool display a message telling me that the tune was already installed and a message that tells : you can unplug the tool and drive, so I just unplug the tool and start the engine and drive, the deam truck feels smooth and the added power can feel it when pedal goes to bottom, but the only thing is that the OIL GAUGE stops to work... it is normal??? Or Do I miss some step ?? Can you please help me...