Extentions failings

I’m having some trouble with installing and using extentions.

I;ve read:
fuzzy_bears => FuzzyBearsExtension
page_attachments => PageAttachmentsExtension

cd /vendor/extensions

language_redirect page_attachments

but when I run rake production db:migrate:extensions

I get
rake aborted!
uninitialized constant LanguageRedirectExtension

The same for PageAttachments when I try to update that one.

I’m on the edge of radiant. revision: 449

Anyone some insight?