IIS7 returns 404 on some static files, not others

Question

I have a css file and a js file in a directory. The css file returns 200 OK while the js file returns 404 Not Found.

They have the same permissions. IUSR, IIS_IUSRS, Internet Guest Account all have (at least) Read.

Answer 1

Add the file type to IIS MIME TYPES. It wont serve unknown file types.