That is a permissions issue. You need to have the correct file permissions set to allow OTRS to change the config

From: otrs-bounces@otrs.org [mailto:otrs-bounces@otrs.org] On Behalf Of Zsolt Hajduk
Sent: Monday, March 11, 2013 9:01 AM
To: otrs@otrs.org
Subject: [otrs] OTRS statistics with ticket owner? - Error message

Dear Michiel Beijen,

I just read the following mail what you sent with the solution.

I got an error message when I want to activate this option:
Framework -> Frontend::Agent::Stats => Stats::UseAgentElementInStats = yes

Would you be so kind to help me about it?
I would be so happy if you can help me.

The Error message is the following:

"Oops! An Error occurred.

Error Message: Can't write ConfigItem!

You can or go back to the previous page.

Error Details

Backend ERROR: OTRS-CGI-10 Perl: 5.10.1 OS: linux Time: Wed Mar 6 10:11:05 2013 Message: Can't write ConfigItem! Traceback (1774): Module: Kernel::Modules::AdminSysConfig::Run (v1.119.2.1) Line: 174 Module: Kernel::System::Web::InterfaceAgent::Run (v1.64) Line: 868 Module: ModPerl::ROOT::ModPerl::Registry::opt_otrs_bin_cgi_2dbin_index_2epl::handler (unknown version) Line: 46 Module: (eval) (v1.90) Line: 204 Module: ModPerl::RegistryCooker::run (v1.90) Line: 204 Module: ModPerl::RegistryCooker::default_handler (v1.90) Line: 170 Module: ModPerl::Registry::handler (v1.99) Line: 31 "

Best regards,
Zsolt