Trouble with ms:type-is Example

I am trying to use the Microsoft XPath extension function: type-is. The documentation for this function is available here:https://msdn.microsoft.com/en-us/library/ms256457(v=vs.110).aspx and this page contains an example.

When I copy/paste the example code from the webpage and attempt to use it in the Visual Studio xslt processor, I receive the following error:

I am using Visual Studio 2013. It seems the type-is function does not work as expected.

I receive the same error, in the form of a System.Xml.Xsl.XslTransformException, when I call the Transform() method of a XslCompiledTransform in a simple console application.

Is there something wrong with the example, or something I may have easily overlooked?