Plesk 11.x / Linux :: Update Of Parallels Panel Has Failed

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

Code:
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):

Code:
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

[code]....

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.