can't upgrade to 13.10 release

[Dirk Broer]

Could not calculate the upgrade (13.04 -> 13.10)

An unresolvable problem occurred while calculating the upgrade.

 This can be caused by:
 * Upgrading to a pre-release version of Ubuntu - no
 * Running the current pre-release version of Ubuntu - no
 * Unofficial software packages not provided by Ubuntu - ?

If none of this applies, then please report this bug using the command 'ubuntu-bug ubuntu-release-upgrader-core' in a terminal.

ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: ubuntu-release-upgrader-core 1:0.192.13
ProcVersionSignature: Ubuntu 3.8.0-32.47-generic 3.8.13.10
Uname: Linux 3.8.0-32-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.9.2-0ubuntu8.4
Architecture: amd64
CrashDB: ubuntu
Date: Fri Oct 18 12:25:53 2013
InstallationDate: Installed on 2013-04-18 (182 days ago)
InstallationMedia: Xubuntu 12.10 "Quantal Quetzal" - Release amd64 (20121017.1)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
UpgradeStatus: Upgraded to raring on 2013-10-18 (0 days ago)
VarLogDistupgradeTermlog: