Unable to add to CD to software sources

[rams123]

I am trying to add Kubuntu CD to Softwares Sources in Ubuntu and got the below error, even though I inserted CD..

http://img6.imageshack.us/img6/7157/screenshot001s.png

Any ideas?

PS. I'm trying to add Kubuntu CD in Ubuntu sources because I want to install Kubuntu desktop in ubuntu by using sudo apt-get install kubuntu-desktop command. I've slow connection, so installing from CD is better option :)

[Sam Lars]

If you click OK does it come back up? I had to click through that even though there was a disk in.