Problem creating XSL Attribute!

Hi all,

A simple question. I am trying to create a onMouseOver attribute on a html
list element. When I use the code below, nothing is outputted to the
browser, I assume indicating a problem? Any help is appreciated.

<xsl:template match="df_data">
  <li>
    <a href="index.php?page={@document_id}">
      <xsl:value-of select="@document_name"/>
    </a> 
    <xsl:if test="child::df_data">
	<xsl:attribute name="onMouseOver">
        onMouseOver="changeClass({child::df_data/@document_id},'close');"
      </xsl:attribute>
	<ul id="{child::df_data/@document_id}">
	  <xsl:apply-templates select="child::df_data"/>
      </ul>
    </xsl:if>
   </li>
</xsl:template>

Cheers,
Adam