I'm just about 100% sure here, but someone correct me if I'm wrong... - The 7912 requires the logo to be added to the firmware of the phone. You actually make a new firmware file using a logo tool that Cisco has, and then force that load out to your phones and the logo appears. Thusly no thumbnail is needed, becuase it is an on or off change, not just something that the user can choose.
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.