XSLT: replace XML value with current date and time

I have the following XML document:

<soapenv:Envelope xmlns:soapenv="http://ift.tt/sVJIaE">
<soapenv:Header/>
<soapenv:Body>
    <Elaborations>
        <Elaboration>
            <DateBegin>2014-01-01T02:00:00.000+01:00</DateBegin>
            <DateEnd>2014-01-01T02:00:00.000+01:00</DateEnd>
            <Result>12594</Result>
        </Elaboration>
        <Elaboration>
            <DateBegin>2014-01-01T02:00:00.000+01:00</DateBegin>
            <DateEnd>2014-01-01T02:00:00.000+01:00</DateEnd>
            <Result>12593</Result>
        </Elaboration>
        <Elaboration>
            <DateBegin>2014-01-01T02:00:00.000+01:00</DateBegin>
            <DateEnd>2014-01-01T02:00:00.000+01:00</DateEnd>
            <Result>12595</Result>
        </Elaboration>
        <Elaboration>
            <DateBegin>2014-01-01T02:00:00.000+01:00</DateBegin>
            <DateEnd>2014-01-01T02:00:00.000+01:00</DateEnd>
            <Result>29598</Result>
        </Elaboration>
        <Elaboration>
            <DateBegin>2014-01-01T02:00:00.000+01:00</DateBegin>
            <DateEnd>2014-01-01T02:00:00.000+01:00</DateEnd>
            <Result>37583</Result>
        </Elaboration>
    </Elaborations>
</soapenv:Body>
</soapenv:Envelope>

I want to replace the values of the elements DateBegin and DateEnd with the current date and time, with XSLT. I wrote the following transformation:

<?xml version="1.0"?>
<xsl:stylesheet version="2.0" xmlns:xsl="http://ift.tt/tCZ8VR">
    <xsl:template match="@*|node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>
    <xsl:variable name="dateNow" select="current-dateTime()"/>
    <xsl:template match="DateBegin/text()">
        <xsl:value-of select="$dateNow"/>
    </xsl:template>
    <xsl:template match="DateEnd/text()">
        <xsl:value-of select="$dateNow"/>
    </xsl:template>
</xsl:stylesheet>

But I'm getting a parse error. Where is the problem?