关于XSLT转换treeview的问题

Question

我的代码为：
<?xml   version="1.0"   encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0" >
<xsl:output method="html" encoding="utf-8"/>
  <xsl:template match="/NewDataSet">
        <TREENODES>
          <xsl:for-each select="roleds">
            <treenode>
              <xsl:attribute name="text">
                <xsl:value-of select="roleName"/>
              </xsl:attribute>
              <xsl:for-each select="roleds">
                <treenode>
                  <xsl:attribute name="text">
                    <xsl:value-of select="roleName"/>
                  </xsl:attribute>
                  <xsl:attribute name="NavigateUrl">
                    <xsl:value-of select="roleValue"/>
                  </xsl:attribute>
                  <xsl:attribute name="Target">
                    main
                  </xsl:attribute>
                </treenode>
              </xsl:for-each>
            </treenode>
          </xsl:for-each>
        </TREENODES>
  </xsl:template>
</xsl:stylesheet>为什么当点击一个treenode的时候，页面不能跳转到我制定的target＝“main”中，而是打开新页面呢？？急求解