I didn`t realize that you are trying to import an already downloaded skin.
I have tested that scenario, and everything works as expected. I have created new skin using Visual Style Builder, then I have made some changes, saved it, downloaded it, and imported it again in the visual style builder and all changes that I made first time were saved. You could see my test at: http://screencast.com/t/fw7bQhaFN
Note that if you zipped your file with several suborders, then the Visual Style Builder could give you an error during the import process. To be successfully added, you should keep your skin files in the main folder and not in sub-folders.
unzipped.gif shows how my unzipped custom skin look like, that was successfully imported into the visual style builder as you could see from the video.
the Telerik team
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