the skin name corresponds to the skin folder name, all it takes is finding the row for the site in the mp_Sites table and change the value in the field named Skin.
or a query like
UPDATE mp_Sites
SET Skin = 'styleshout-envision'
WHERE SiteID = 1
(Assuming this is a single site installation then the site id will be 1, if a multi site installation you will need to determine the site id)
styleshout-envision is a skin we ship in the /Data/skins folder, you should copy it to the /Data/Sites/[SiteID]/skins folder
alternatively you could zip up your skin and email it to me so I can test it and see if I can produce the error or if I notice anything unusual about how it is configured.
Hope it helps,
Joe