I wonder if that theme is blocked somehow? You can check if a group policy was enabled.
http://www.dell.com/support/article/...dows-7?lang=en
Interestingly, ALL the settings are showing as Not configured.
I disabled the "Prevent changing color scheme" but it didn't enabled the greyed out themes. Should I "configure" all of them before going to the next step?

I also checked my laptop, which displays the themes correctly, and none of the settings are configured either. (i thought of copying the settings)