Evaluating text from within an attribute tag

This looks similar to a question I asked earlier, but
is infact different. I have a template that I call and
pass in parameters and when I run the template they
aren't getting evaluated, i.e:

<xsl:template name="fill_path">
    <xsl:param name="x_offset" select="0" />
    <xsl:param name="y_offset" select="0" />
    <xsl:param name="fill_percentage" select="0" />
    <xsl:param name="fill_limit" select="0" />
        
    <xsl:attribute name="d">M {$x_offset} {$y_offset}
v 73 a 2 2 0 1 1 -4 0 v -73 Z</xsl:attribute>
                            
</xsl:template>

The output of this is "...{$x_offset} {$y_offset}..."

Thanks for any help,

Bryan

__________________________________________________
Do You Yahoo!?
Yahoo! Sports - live college hoops coverage
http://sports.yahoo.com/

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