Can't use themes on Sansa Clip+

[alwaysopen]

I installed Rockbox on a Sansa Clip+, and it works fine, but I can't use any themes. I installed the theme pack with a few themes, but they don't show up under the themes menu on the device. Can someone explain what I am doing wrong? I'm new to this kind of stuff. Thanks for any help

[saratoga]

I would check that the themes got copied to the right drive letter or mount point.  Often when people say installing didn't work its because they've inadvertently copied things to their internal hard drive by mistake.