ubuntustudio-9.04-alternate-i386.iso/cdromupgrade KO

Binary package hint: ubuntu-docs

sudo mount iso whith nautilus script :
#!/bin/bash
#
# nautilus-mount-iso

gksudo -u root -k /bin/echo "got r00t?"

sudo mkdir /media/"$*"

if sudo mount -o loop -t iso9660 "$*" /media/"$*"
then
        if zenity --question --title "ISO Mounter" --text "$* Successfully Mounted.

        Open Volume?"
        then
                nautilus /media/"$*" --no-desktop
        fi
        exit 0
else
        sudo rmdir /media/"$*"
        zenity --error --title "ISO Mounter" --text "Cannot mount $*!"
        exit 1
fi

 sudo sh /media/ubuntustudio-9.04-alternate-i386.iso/cdromupgrade

Include last update from internet : NO
gpgv: Signature made Tue 21 Apr 2009 09:52:30 PM CEST using DSA key ID FBB75451
gpgv: Good signature from "Ubuntu CD Image Automatic Signing Key <email address hidden>"

Can't install 'ubuntu-desktop'

It was impossible to install a required package. Please report this as a bug.

Could not calculate the upgrade

An unresolvable problem occurred while calculating the upgrade:
The package 'skype' is marked for removal but it is in the removal blacklist.

 This can be caused by:
 * Upgrading to a pre-release version of Ubuntu
 * Running the current pre-release version of Ubuntu
 * Unofficial software packages not provided by Ubuntu

If none of this applies, then please report this bug against the 'update-manager' package and include the files in /var/log/dist-upgrade/ in the bug report.