package libgtk2.0-cil 2.12.9-4 failed to install/upgrade:

[Ursus11]

Binary package hint: gtk-sharp2

Upgrading Ubuntu to version 10.04 LTS from the latest 9.xxx
I cannot see the previous version System->About Ubuntu presents already 10.04

ProblemType: Package
DistroRelease: Ubuntu 10.04
Package: libgtk2.0-cil 2.12.9-4
ProcVersionSignature: Ubuntu 2.6.31-21.59-generic
Uname: Linux 2.6.31-21-generic i686
Architecture: i386
Date: Sat May 15 08:35:00 2010
ErrorMessage:
 ErrorMessage: subprocess installed post-installation script returned error exit status 1
InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release i386 (20091028.5)
SourcePackage: gtk-sharp2
Title: package libgtk2.0-cil 2.12.9-4 failed to install/upgrade: