sitemap localization not working

Strange things happening. If I have only one file filename.en-US.resx file in App_GlobalResour开发者_如何学JAVAces. Sitemap(Which is referring as "$resources:Web.sitemap,key") is throwing error that object or key couldnt find. But when i have two files filename.en-US.resx and filename.resx[this has no keys it is empty], sitemap is working fine. Please need some explanation.

I think you need to have a filename.resx that acts as the normal (invariant) resource before adding culture/language specific resource files.