NAMESPACE_ERR when creating element with namespace

I don't understand.
I am using saxon 8.8 for java and xerces 2.6.1

This simple example will replicate a XML document by adding a
namespace to each nodes:

   <xsl:template match="*">
       <xsl:element name="{local-name()}" namespace=http://mynamespace>
           <xsl:apply-templates/>
       </xsl:element>
   </xsl:template>

Caused by: org.w3c.dom.DOMException: NAMESPACE_ERR: An attempt is made
to create or change an object in a way which is incorrect with regard
to namespaces.
at org.apache.xerces.dom.AttrNSImpl.setName
at org.apache.xerces.dom.AttrNSImpl.<init>
at org.apache.xerces.dom.CoreDocumentImpl.createAttributeNS
at org.apache.xerces.dom.ElementImpl.setAttributeNS
at net.sf.saxon.dom.DOMWriter.namespace(DOMWriter.java:118)
... 132 more

the problem occurs when the first node is created ... DOMWriter create
the attribute xmlns="html://mynamespace" and my Xerces impl throws a
DOMException