Update of Parallels Panel has failed

[VojkanC]

Hi,

I have Parallels Plesk Panel v.11.5.30 on CentOS (Linux version 2.6.32-431.3.1.el6.x86_64) and I get error message whenever Plesk tries autoupdates.
Problem started to appear just after I updated server with atomicorp
This is the topic that I followed: http://forum.parallels.com/showthread.php?302688-Update-PHP-and-MySQL-easiest-way&p=729623

When I try to update manually through console (yum update) I get following error:

warning: rpmts_HdrFromFdno: Header V3 RSA/SHA1 Signature, key ID 4520afa9: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY.art.txt


The GPG keys listed for the "CentOS / Red Hat Enterprise Linux 6 - atomicrocketturtle.com" repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.

When I try to update any component manually through panel I get following error (This is for Apache web server support):

Installation started in background
Loaded plugins: fastestmirror, priorities
Loading mirror speeds from cached hostfile
* atomic: www7.atomicorp.com
* base: mirror.checkdomain.de
* extras: mirror.checkdomain.de
* updates: mirror.checkdomain.de
202 packages excluded due to repository priority protections
+ mysql-server
+ httpd
+ mysql
+ mod_ssl
+ httpd-tools
+ mysql-libs

Installing packages
Loaded plugins: fastestmirror, priorities
Loading mirror speeds from cached hostfile
* atomic: www7.atomicorp.com
* base: ftp.hosteurope.de
* extras: ftp.hosteurope.de
* updates: ftp.hosteurope.de
202 packages excluded due to repository priority protections
warning: rpmts_HdrFromFdno: Header V3 RSA/SHA1 Signature, key ID 4520afa9: NOKEY
Retrieving key from file:///etc/pki/rpm-gpg/RPM-GPG-KEY.art.txt
Fatal error during packages installation: The GPG keys listed for the "CentOS / Red Hat Enterprise Linux 6 - atomicrocketturtle.com" repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.
YumBaseError: The GPG keys listed for the "CentOS / Red Hat Enterprise Linux 6 - atomicrocketturtle.com" repository are already installed but they are not correct for this package.
Check that the correct key URLs are configured for this repository.
Error: Failed to run the Yum utility.
The Yum utility failed to install the required packages.
Attention! Your software might be inoperable.
Please, contact product technical support.

Can someone please troubleshoot this problem, so that I can update successfully, either manually or automatically?