My global resource designer file is empty when I add culture to the file name

I am writing a asp.net web application with multi-language support. I want to 开发者_如何学运维add a resource to the App_GlobalResources file called "GlobalStrings". When I name the file GlobalStrings.resx, everything is fine. But when I add a file called GlobalStrings.en-US.resx the designer file behind it is empty (no text at all) an nothing appears in intellisense. Any ideas?

The deal is that there must be one resource file (default) without culture added.