HTML processing Error - Rx5.7

Evening all.
Having a bit of a problem and can’t fathom why this isn’t working. I keep being given the following error message when trying to preview:

An exception occurred while processing the whitebox XML document through the file:PO_freetext_cas/s_FreeTextToolTips.xsl style sheet: org.xml.sax.SAXParseException: The element type “xsl:attribute” must be terminated by the matching end-tag “</xsl:attribute>”. [Error data in range: <!–end XSL –></span> </xsl:template></xsl:stylesheet>]

This is the code:

	<!-- begin XSL -->
	<xsl:value-of select="//header" />
	<!-- end XSL -->
<img class="ContextualHelp" src="images/icon_q.gif" height="11" width="11">
    <!-- begin XSL -->
    <xsl:attribute name="title">
    <xsl:value-of select="//shared/body/div/p" />
    <xsl:attribute name="alt">
    <xsl:value-of select="//header" />
    <!--end XSL -->

Any ideas would be greatly appreciated.