You need to setup de upgrade package…

http://faq.otrs.org/otrs/public.pl?Action=PublicFAQ&CategoryID=14&ItemID=300

you cannot install the itsm 1.1  packages…( ITSMTicket-1.1.3.xml

LinkObject2-1.1.3.xml

)

use the 1.2 versions!!!

when you use otrs 2.3 you have to install itsm 1.2 packages:

http://mirror.globalcore.net/otrs/itsm/INSTALL-1.2.ITSM

2. Installation OTRS::ITSM 1.2

------------------------------

   a) Login to your OTRS 2.3 installation with admin permissions.

   c) Install the downloaded .opm packages in the following order

      via package manager:

        1) GeneralCatalog

        2) ITSMCore

      If your OTRS is able to connect to the internet, you can use now

      the online repository [--OTRS::ITSM 1.2 Master--] to install the

      following packages. If your OTRS is unable to connect to the

      internet, you need to install the following packages via package

      manager. Each of these packages is optional and there is no

      required installation order.

        -ITSMIncidentProblemManagement

        -ITSMConfigurationManagement

        -ITSMServiceLevelManagement

        -ImportExport

Regards,

Josy