param problem

Hello:

I have a xsl using exslt.org/functions

<?xml version="1.0" encoding="ISO8859-1" ?>
<xsl:stylesheet version="2.0"
    xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
    xmlns:func="http://exslt.org/functions"
    xmlns:gti="http://www.gtinformatica.pt">
 
  <func:function name="gti:facton">
    <xsl:param name="val"/>
    <func:result select="round($val div 14)"/>
  </func:function>
 
</xsl:stylesheet>

wich i'm importing into another

<?xml version="1.0" encoding="ISO8859-1" ?>
<xsl:transform version="2.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" version="1.0" encoding="iso-8859-1" 
indent="yes"/>
  <!-- Funções -->
  <xsl:include href="xfunctions.xsl" />
  (...more stuff...)

No i want to pass a parameter from a Java program to this XSLT, so i have
 
<?xml version="1.0" encoding="ISO8859-1" ?>
<xsl:transform version="2.0" 
xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:output method="xml" version="1.0" encoding="iso-8859-1" 
indent="yes"/>

 <xsl:param name="sqlvars" select="'default'" />

  <!-- Funções -->
  <xsl:include href="xfunctions.xsl" />
  (...more stuff...)

but i allways get this error:

javax.xml.transform.TransformerException: 
javax.xml.transform.TransformerException: An EXSLT function cannot set 
more than one result!

What is going on? I use Xalan Java 2.4.1