xsl:apply-templates in combination with xsl:choose

Hi!

I'm stuck on a problem quite a while now and am glad for help.
I'm trying to convert multiple input documents. They are have a highly
different structure so I'm trying to let xslt divide them before they
get processed further (using oxygenxml with built-in SAXON8B). 

I have a xml which holds the list of documents this way:
<filesystem>
 <file>filename1.xml</file>
 <file>filename2.xml</file>
 <file>filename3.xml</file>
 <file>filename4.xml</file>
</filesystem>

and a xsl that matches first on filesystem, gives a list of the files
and then I try to separate the files depending on something the contain
or not:

<xsl:template match="filesystem">
.....

<xsl:choose>
 <xsl:when
test="file/document(.)/xh:html/xh:head/xh:link/attribute::rel[contains(.,'stylesheet')]">
   <xsl:apply-templates select="file" mode="neuerTest"/>
 </xsl:when>

 <xsl:when
test="file/document(.)/xh:html/xh:head/xh:title[contains(.,'Mag')]">
  <xsl:apply-templates select="file" mode="#default"/>
 </xsl:when>
</xsl:choose> 

</xsl:template>

<xsl:template match="file" mode="neuerTest">
...
<xsl:template>

<xsl:template match="file" mode="#default">
...
<xsl:template>

The problem is that the first 'when' always turns true. So all files are
processed using the first argument. I tried testing for the other type
in first place and got the same result: The test I place first is always
true even if I made sure that in the documents to be processed the
things I test for are exclusive. Type B doesn't have a stylesheet
attribute and type A never contains 'Mag' in title. 

There must be a syntactical error or am I using this at the wrong place?
There must be something evident that I am missing. Can you please help
me? I tried to keep this mail short if I left out something important,
please drop me a line.

Many thanks for any help!
Stefanie