question about excel XML maps

Hi expert,

         I am using excel XML maps, I have two questions :

(1) when I add a XML source from internet, such as 'http://rss.cnn.com/rss/edition.rss', get a error message as " this path does not exist", how to eliminate this error?

(2) I use a xml file as source instead, but when I remove this xml source, the dashboard display same content from this removed XML source, even I input different content in same cells in the embedded excel file, please tell how to completely clear up content for removed XML source?

Many Thanks,

Andy