Can't install any software wit USC

When you lunch USC its open but if you try to install any app it don't do nothing. Via terminal when you lunch software center it gives you this information:
software-center
2012-10-31 16:28:59,009 - softwarecenter.ui.gtk3.app - INFO - setting up proxy 'None'
2012-10-31 16:28:59,017 - softwarecenter.db.database - INFO - open() database: path=None use_axi=True use_agent=True
2012-10-31 16:28:59,537 - softwarecenter.backend.reviews - WARNING - Could not get usefulness from server, no username in config file
2012-10-31 16:28:59,950 - softwarecenter.ui.gtk3.app - INFO - show_available_packages: search_text is '', app is None.
2012-10-31 16:28:59,953 - softwarecenter.db.pkginfo_impl.aptcache - INFO - aptcache.open()
2012-10-31 16:29:09,315 - softwarecenter.ui.gtk3.app - INFO - software-center-agent finished with status 0
2012-10-31 16:29:09,316 - softwarecenter.db.database - INFO - reopen() database
2012-10-31 16:29:09,316 - softwarecenter.db.database - INFO - open() database: path=None use_axi=True use_agent=True

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: software-center 5.2.6
ProcVersionSignature: Ubuntu 3.2.0-32.51-generic 3.2.30
Uname: Linux 3.2.0-32-generic x86_64
ApportVersion: 2.0.1-0ubuntu14
Architecture: amd64
Date: Wed Oct 31 16:43:42 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=pt:pt_BR:en
 TERM=xterm
 PATH=(custom, no user)
 LANG=pt_PT.UTF-8
 SHELL=/bin/bash
SourcePackage: software-center
UpgradeStatus: No upgrade log present (probably fresh install)