Sort Problem

Hi
I am trying to pass this parameter
<xsl:param name="sortBy" select="default"/>
to the sort command
<xsl:apply-templates select="Supplier">
  <xsl:sort data-type="number" select="{$sortBy}"/>
</xsl:apply-templates>
but I am getting this error:
Error in xsl processing pattern = '{$sortBy}'
Extra illegal tokens: '$', 'sortBy}'
What is wrong with this call?
My objective is to call the sort depending on a user selection which is
passed to the template using parameters.



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