URIResolver

This may be somewhat off topic for this list so I apoligize in advance.

I've implemented a URIResolver for my transformer calls. For some
reason, when I use the document('') XPATH expression function, the
URIResolver does not get called. Instread I get the error "(The system
cannot find the file specified)". What I've read says that document()
should use URIResolver. Perhaps it's the implenation I'm using?

      <xsl:for-each select="document('facility_map.xml')">
         <xsl:value-of select="key('facilityIDMap', $lookup)/@value"/>
      </xsl:for-each>

My Transformer Factory Implementation is:
org.apache.xalan.processor.TransformerFactoryImpl

-Kevin