XSLT 1.0: copy everything except certain nodes according to value and variable

I have the following (simplified) XML that I get in a system environment:

<?xml version="1.0" encoding="UTF-8"?>
<root>
<IS_LOG>
    <USER>19291</USER>
    <DATE>2011-08-15</DATE>
    <TIME>15:36:36</TIME>
    <SYST>sy1</SYST>
    <MATERIALS>
        <item>
            <sy>100</sy>
            <mat>000000000000310000</mat>
        </item>
        <item>
            <sy>100</sy>
            <mat>000000000000491078</mat>
        </item>
    </MATERIALS>
</IS_LOG>
</root>

The system that I work with passes me a variable at runtime that is not included in the XML structure above.

I have the following XSLT:

<?xml versio开发者_开发知识库n="1.0" encoding="UTF-8"?>
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
xmlns:xd="http://www.oxygenxml.com/ns/doc/xsl" version="1.0">

<!-- System variable whose value I normally only get only at runtime;
for test purposes set locally -->
<xsl:variable name="SenderService" select="'AT'"/>

<xsl:template match="@*|node()">
    <xsl:choose>
        <xsl:when test="$SenderService='AT'">
            <xsl:copy>
                <xsl:apply-templates mode="AT" select="@*|node()"/>
            </xsl:copy>
        </xsl:when>
        <xsl:otherwise>
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
        </xsl:otherwise>
   </xsl:choose> 
</xsl:template>


<xsl:template mode="AT" match="item[mat &gt; 000000000000299999 and mat &lt; 000000000000399999]"/>

</xsl:stylesheet>

Now I need to copy all elements item excluding the ones where mat is in the number range of 300000 to 399999 and SenderService is 'AT'. If to test it locally I change the SenderService in my XSLT to e.g. 'Z', the output looks fine, all items get copied:

<?xml version="1.0" encoding="UTF-8"?>
<root>
<IS_LOG>
    <USER>19291</USER>
    <DATE>2011-08-15</DATE>
    <TIME>15:36:36</TIME>
    <SYST>sy1</SYST>
    <MATERIALS>
        <item>
            <sy>100</sy>
            <mat>000000000000310000</mat>
        </item>
        <item>
            <sy>100</sy>
            <mat>000000000000491078</mat>
        </item>
    </MATERIALS>
</IS_LOG>
</root>

But if I set SenderService to 'AT' the output looks like this:

    <?xml version="1.0" encoding="UTF-8"?><root>

    19291
    2011-08-15
    15:36:36
    sy1
    
        
        
            100
            000000000000491078
        
    

</root>

The correct item gets copied but without the tags. How can I change the XSLT?

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml" indent="yes"/>

    <xsl:variable name="SenderService" select="'AT'"/>

    <xsl:template match="@*|node()">
        <xsl:copy>
            <xsl:apply-templates select="@*|node()"/>
        </xsl:copy>
    </xsl:template>


    <xsl:template match="item[mat &gt; 000000000000299999 and mat &lt; 000000000000399999]">
        <xsl:if test="$SenderService != 'AT'">
            <xsl:copy-of select="."/>
        </xsl:if>
    </xsl:template>

</xsl:stylesheet>