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?

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

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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.