Setting variable based on passed in parameter

I'm trying to assign a variable a node-set that depends on a parameter
passed into the stylesheet.

  <xsl:param name="nodeValue">something</xsl:param>
  <xsl:param name="valueSearch">false</xsl:param>
  <xsl:variable name="initialResult">
      <xsl:choose>
        <xsl:when test="$valueSearch='false'">
            <xsl:value-of
select="/one/two[three/four[contains(text(),$nodeValue)]]"/>
        </xsl:when>
        <xsl:otherwise>
            <xsl:value-of
select="/one/two[three/four[contains(text(),$nodeValue)]]"/>
        </xsl:otherwise>
      </xsl:choose>
  </xsl:variable>
<xsl:template match="/">
      <xsl:apply-templates select="$initialResult"/>
</xsl:template>
<xsl:template match="/one/two">
   ...
</xsl:template>


I get an error in oXygen saying, "Cannot process a result tree fragment
as a node-set  under XSLT 1.0"

Am I doing something wrong?

Thanks in advance. :)

Matthew