plexmediaserver installation problems

Was getting errors on my plexmediaserver install so I uninstalled it and tried to reinstall.
Now getting the following error on the plex tab -

Error

Failed to get configuration (xpath=//services/plexmediaserver)
Error #3003:exception 'OMVException' with message 'Failed to get configuration (xpath=//services/plexmediaserver)' in /usr/share/openmediavault/engined/module/plexmediaserver.inc:82Stack trace:#0 /usr/share/openmediavault/engined/rpc/services.inc(63): OMVModulePlexMediaServer->getStatus()#1 [internal function]: OMVRpcServiceServices->getStatus(Array, Array)#2 /usr/share/php/openmediavault/rpcservice.inc(125): call_user_func_array(Array, Array)#3 /usr/share/php/openmediavault/rpc.inc(79): OMVRpcServiceAbstract->callMethod('getStatus', Array, Array)#4 /usr/sbin/omv-engined(500): OMVRpc::exec('Services', 'getStatus', Array, Array, 1)#5 {main}

ANy ideas how to fix this?

Thanks Wolf, that did it!
I was trying to do it all from the GUI.
Much appreciated.