the namespace associated with schema elements in your stylesheet is wrong;
you should replace
xmlns:x="http://www.ipdr.org/namespaces/IPDR"
with
xmlns:x="http://www.w3.org/2001/XMLSchema"

Hi,
 (...)
  E.g. XSD input file (sample)
  <schema>
  <schema xmlns = "http://www.w3.org/2001/XMLSchema"

  My XSL
  ======
  <?xml version="1.0" encoding="ISO-8859-1" ?>
<!--  Edited with XML Spy v2006 (http://www.altova.com) -->
<xsl:stylesheet version="1.0"
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:x="http://www.ipdr.org/namespaces/IPDR">

<xsl:template match="x:schema">