I don't know either u got the proper driver ! Please download the proper driver from here:
www.dell.com/support/drivers/us/en/04/DriverDetails/DriverFileFormats?DriverId=R267660
this file almost 24 mb in size and after clicking "Download File", there will be a dialog box, select the first one, i.e. "For Single File Download....." and then click Download Now. After downloading extracting the file and it will create a folder called "cdroot" and u need to run the autorun file as:
cd cdroot
sudo ./autorun

Hope it works.