Windows 7 Theme Question - Themes not changing?

Before I go any further I do know how to change the desktop theme in Windows 7. I have Win 7 Ultimate at home. I have a custom theme setup on that computer.

I am using Windows 7 Professional on a networked computer at work. I have researched this problem and have come across no workable solution.

The themes are not grayed out and a custom theme is the default theme setup associated with the organization that I work for. This is a networked computer and I DO NOT have administrative sign on ability. I cannot sellect a different theme.

So with all this being said does anyone know how to allow changing of the desktop theme?

Please spare your time by telling me that I need to right click on the desktop (or get there some other way) and left click on "Personalize". And then click on the theme I want to use, it does not work, that is my problem!!!