Value-of varible question

For some reason this won't work 
<xsl:param name="local" select="en-EN"/>
<xsl:template match="Title">
                <Title>
                        <xsl:copy-of
select="/iThink.ePulp/Page/Content/Meta/Title[(_at_)lang=$local]"/>
                </Title>
        </xsl:template>
But this will
<xsl:template match="Title">
                <Title>
                        <xsl:copy-of
select="/iThink.ePulp/Page/Content/Meta/Title[(_at_)lang='en-EN']"/>
                </Title>
        </xsl:template>

Does anyone know why and is there a way I can get around it?