Make sure that the media  shown by the black arrows below match.  If they do not, change the media type selection by clicking on the media settings button shown to the right of the screen with the red arrow.  Clicking on this button brings up your material options so you can match the one selected on the job file.  

If your printer has the correct media selected but the job is not selected correctly, simply right click on the job in queue and select "Job Properties" and change the media there to match the machine.