Cannot install shell-themes using gnome-tweak-tool

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http://askubuntu.com – How do I fix this? I will attempt to upload a screenshot of the problem. Notice there is an error like triangle near the shell themes and nothing is select-able. Also there are no shell extensions under the shell extensions tab. I have come across many postings on how to fix this but none worked for me. I currently have 12.04 LTS. I have a custom Phenom quad core machine with Radeon HD 5770 graphics if that helps. (HowTos)