how to pass arguments to xt extension functions ?

I am trying to figure out how to pass string arguments to 
xt extension functions.  I can not get the following to work:

<xsl:stylesheet xmlns:xsl="http://www.w3.org/XSL/Transform/1.0"
           xmlns:w="http://www.jclark.com/xt/java/sqlxml" >
<xsl:template match="cis">
   <xsl:variable name="this" expr="w:new()" />
   <xsl:variable name="usr"  expr="@name" /> 
   <xsl:value-of select="$usr" />                                    <!--
this returns the correct value -->
   <xsl:value-of select="w:con1($this, string($usr) )" />   <!-- this yields
an illegal arguments error -->
</xsl:template>
</xsl:stylesheet>	

where the xml is:
<cis name="sa">
  <database>jdbc:odbc:cis </database>
</cis>

and where con1 is declared as:
	public String con1 (String user)

I must be missing something obvious here.  Below
are two working examples that correctly handle
this arguments and strings.  I just can't the combined
example to work....

I have tried numerious variations, but suggestions would
be welcomed!  Or if anyone has got this working I would
love to get a definitive answer.  Thanks to all!



------------------these samples work -------------------
------------------together they show how to 
------------------use this pointers and how to
------------------use string arguments.....

Here is short demo that works:
   <xsl:stylesheet xmlns:xsl="http://www.w3.org/XSL/Transform/1.0" 
 
xmlns:w="http://www.jclark.com/xt/java/com.jclark.xsl.sax.TextFileWriter">

   <xsl:template match="file">
       <xsl:variable name="file" expr="@name"/>
      <xsl:variable name="contents"><xsl:apply-templates/></xsl:variable>
       <!-- -->
       <xsl:value-of select="w:write($contents, string($file) )"   />
   </xsl:template>

</xsl:stylesheet>

where write is declared as :
    static public void write(ResultTreeFragment frag, String file)

--------------------------------
--------------------------------

this also works:
   <xsl:stylesheet xmlns:xsl="http://www.w3.org/XSL/Transform/1.0"
           xmlns:w="http://www.jclark.com/xt/java/sqlxml" >

    <xsl:template match="cis">
         <xsl:variable name="this" expr="w:new()" />
         <xsl:variable name="usr"> <xsl:value-of select="user" />
</xsl:variable>
         <xsl:value-of select="w:con($this )" /> 
    </xsl:template>

    </xsl:stylesheet>

where con is declared
     public String con ()


Brian Smith


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