XSL Xalan extension problem

Hi,

I'm beginning with SXL extensions and I tried the example below but only got
XSLT Error (javax.xml.transform.TransformerException): 
java.lang.NoSuchMethodException: For extension function,  could not find 
method org.apache.xml.utils.NodeVector.convertDate([ExpressionContext,] ).
I don't understand what it corresponds to or where I'm wrong.

Could somebody help me please ?
Many Thks,

-------------
Java class : Converter
-------------

package TestXalan;

public class Converter
{

 public Converter()
 {
 }

 public String convertDate(String aDate)
  {
     String aString ="";
     // (...)
     return aString;
  }
}

------------------
XLS sheet : ConvertCat002.xsl
-----------------

<?xml version="1.0"?>
<xsl:stylesheet version="1.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform"; 
xmlns:xalan="http://xml.apache.org/xalan"; 
xmlns:my-class="java:TestXalan.Converter">
        <xalan:component prefix="my-class" functions="convertDate">
                <xalan:script lang="javaclass" 
src="xalan://TestXalan.Converter"/>
        </xalan:component>
        <xsl:output method="xml"/>
	<xsl:template 
match="ReservationEffectiveDate|TicketingEffectiveDate|TravelEffectiveDate">
        <xsl:variable name="date" select="."/>
                <xsl:value-of select="my-class:convertDate($date)"/>
        </xsl:template>
</xsl:stylesheet>

--------------
and I'm calling

@java -classpath 
C:/xerces-2_6_0/xercesImpl.jar;C:/jwsdp-1.3/jaxp/lib/endorsed/xalan.jar;lib/bsf.jar;lib/bsfengines.jar;classes 
org.apache.xalan.xslt.Process -in Cat002.xml -xsl ConvertCat002.xsl -out 
ConvertedCat002.xml
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