This is working as designed in CUCM 6.x. The ability to turn mobile connect on/off from the phone was added in CUCM 7. The only time you will see an option on this softkey is when you are on a call. It will give you the option to send the call to your mobile phone.
Are you getting this error “Installer User Interface Mode Not Supported. The installer cannot run in this UI mode. To specify the interface mode, use the -i command-line option, followed by the UI mode identifier. The value UI mode identifiers...
The below trick might come handy when you have to add a new node to a cluster but you don't have or is unsure of the security password for the publisher. This procedure has been around for ages.
1) Login into the CLI of the Publisher.