Application.GetContentStream returns null for content Uri

I have file "sam开发者_StackOverflowple.xml" in my project set as content.

I am running this code:

  Uri uri = new Uri("/sample.xml", UriKind.Relative);
  StreamResourceInfo contentStream = Application.GetContentStream(uri);

Why it returns null contentStream?

You must set file's Build Action as Content, and Copy To Output Directory to Copy Always or Copy if newer.

It means probably that it does not find the file. Is the path correct?.

Return Value

Type: System.Windows.Resources.StreamResourceInfo

A StreamResourceInfo that contains a content data file that is located at the specified Uri. If a loose resource is not found, null is returned.