Troublshooting XSLT replace()

I'm glad my last query produced some mirth. I've got another today.

The "Undate" and "Circa" modes do not work in the following stylesheet
and I can't figure out why. Can someone please point out my errors?

Many thanks,
Nathan

<xsl:stylesheet version="2.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml"
        doctype-public="+//ISBN 1-931666-00-8//DTD ead.dtd (Encoded
Archival Description (EAD) Version 2002)//EN"
        doctype-system="ead.dtd" indent="yes"/>
    <xsl:variable name="vAllowedSymbols"
        select="'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789
-.'"/>
    <xsl:template match="* | processing-instruction() | comment()">
        <xsl:copy>
            <xsl:copy-of select="@*"/>
            <xsl:apply-templates/>
        </xsl:copy>
    </xsl:template>
    <xsl:template match="*/text()">
        <xsl:variable name="phase1">
            <xsl:apply-templates select="." mode="Punctuation"/>
        </xsl:variable>
        <xsl:variable name="phase2">
            <xsl:apply-templates select="$phase1" mode="Undate"/>
        </xsl:variable>
        <xsl:variable name="phase3">
            <xsl:apply-templates select="$phase2" mode="Circa"/>
        </xsl:variable>
        <xsl:apply-templates select="$phase3" mode="Extent"/>
    </xsl:template>
    <xsl:template
        match="unittitle/text()[matches(., '^.*\p{P}$')] |
unittitle/title/text()[matches(., '^.*\p{P}$')] |
unitdate/text()[matches(., '^.*\p{P}$')]"
        mode="Punctuation">
        <xsl:sequence select="replace(., '(^.*)\p{P}$', '$1')"/>
    </xsl:template>
    <xsl:template match="unitdate/text()" mode="Undate">
        <xsl:sequence select="replace(., 'Undated','undated')"/>
    </xsl:template>
    <xsl:template match="unitdate/text()" mode="Circa">
        <xsl:sequence select="replace(., 'Circa','circa')"/>
    </xsl:template>
    <xsl:template match="physdesc/extent/text()" mode="Extent">
        <xsl:value-of select="translate(.,translate(.,
$vAllowedSymbols, ''),'')"/>
    </xsl:template>
    <xsl:template match="unittitle[not(string(.))]"> </xsl:template>
</xsl:stylesheet>