variable select on xsl:apply-templates

In general I am trying to create a call-able, generic template for a
deep, static, surrounding structure with variable content.
It looks something like this:
<xsl:template name="FormLayout">
      <xsl:param name="action"/>
      <xsl:param name="formName"/>
      <xsl:param name="formCallBack"/>

       <!--Complicated many layered structure-->
              <xsl:apply-templates>
                     <xsl:value-of select="$formCallBack"/>
               </xsl:apply-templates>
       </!--Complicated many layered structure-->
</xsl:template>

I am getting different behavior from 2 different xslt processors (MS and XT).
XT accepts the code and MS posits an unexpected child error.

In both processors if I attempt to evaluate the variable as part of
<xsl:apply-templates select="$formCallBack"/>, it fails.

However XT will accept the following:
<xsl:apply-templates>
     <xsl:value-of select="$formCallBack"/>
 </xsl:apply-templates>
(it accepts it as long as $formCallBack is a simple, top level xpath reference)


Is this code permissible?
Is this a case where I need to evaluate the argument in the select?
Is there a better solution?

Thanks for any help,
ap




 XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list