result with with header... on mono and .net the same empty xml

gistfile1.txt

	string transform = "<?xml version=\"1.0\" encoding=\"utf-8\"?>"+
"<xsl:stylesheet version=\"1.0\" xmlns:xsl=\"http://www.w3.org/1999/XSL/Transform\"> " +
	"<xsl:template match=\"*\"> " +
		"<xsl:variable name=\"a\" select=\"'a'\"/> " +
		"<xsl:value-of select=\"*[@a=$a]\"/> " +
	"</xsl:template> " +
"</xsl:stylesheet>";
			XmlReader rd = new XmlTextReader( new StringReader(transform));
			
			
			
			
			
			XslTransform tr = new XslTransform();
			 tr.Load(rd);
			
			tr.Transform("a.xml","b.xml");