[xubuntu] Wall paper image list option doesn't work .

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http://ubuntuforums.org – I'm using Xubuntu 12.10. In the Desk Top section of the Settings there is an option to use an image list for wall papers and it will change the wall paper randomly at an interval you can set in the settings. I have added the images I want and set the time interval but it doesn't do anything. Am I doing something wrong or is this a bug or something else? (Hardware)