"HTTP Error 404.3 - Not Found" force download of .step file in IIS7.5

I have a website in witch i need to enable download of .step files. I try to add an handler in IIS but I stil get an error.

My handler is :

• Path : *.step
• Path Type : File or Folder
• Handler : StaticFileModule,DefaultDocumentModule,DirectoryListingModule

So it's the same as StaticFile, anyone can tell me why staticFile handler is not taking care of these files?

The error I get is :

HTTP Error 404.3 - Not Found The page you are requesting cannot be served because of the extension configuration. If the page is 开发者_如何学编程a script, add a handler. If the file should be downloaded, add a MIME map.

This is in a MVC.Net application

Thank you!

Did you create a MIME map? see: http://sebastienlachance.com/post/Adding-a-MIME-map-in-IIS.aspx