IDVD Themepak installation issue

I purchased third party themes from ThemePaks and when I try to install the software, I get to the part that ask's "What volume that I want to install this on and when I choose the destination I get an error that says "you are not allowed to install the software in the default location on the volume "Final Cut" Check with the administrator of your computer (final cut is the name of my main drive) When I try to install the PAK Free installer pkg. it however does let me install the free pak. I am the admin and the only user, I have tried repairing my permissions and still get the same message. I tried installing other software after this and it installs fine. Can anyone please help.. Apple and Themepak are out of answers....