package libgksu2-0 2.0.13~pre1-6ubuntu2.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 127

can't update upgrade

ProblemType: Package
DistroRelease: Ubuntu 13.04
Package: libgksu2-0 2.0.13~pre1-6ubuntu2.1
ProcVersionSignature: Ubuntu 3.8.0-30.44-generic 3.8.13.6
Uname: Linux 3.8.0-30-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.9.2-0ubuntu8.3
Architecture: amd64
Date: Tue Sep 17 04:57:59 2013
DuplicateSignature: package:libgksu2-0:2.0.13~pre1-6ubuntu2.1:subprocess installed post-installation script returned error exit status 127
ErrorMessage: subprocess installed post-installation script returned error exit status 127
InstallationDate: Installed on 2013-09-01 (15 days ago)
InstallationMedia: Ubuntu 13.04 "Raring Ringtail" - Release amd64 (20130424)
MarkForUpload: True
SourcePackage: libgksu
Title: package libgksu2-0 2.0.13~pre1-6ubuntu2.1 failed to install/upgrade: subprocess installed post-installation script returned error exit status 127
UpgradeStatus: No upgrade log present (probably fresh install)