How to set session context in session attribute selector?

[Jan <vi...@gmx.de>]

In session context "layout" I created a node "name".
How can I use the session-attribute selector in sitemap to choose from a set of xsl stylesheets?

I tried to set 
   <attribute-name>/layout/name</attribute-name>
in the session-attribute selector's config

and seting up the pipeline like this:

   <map:match pattern="**.xhtml">
    <map:generate src="cocoon:/{1}.xml"/>
    <map:select type="session-attribute">
     <map:when test="lynx">
      <map:transform src="stylesheets/xhtml/lynx/mux.xsl"/>
     </map:when>
     <map:otherwise>
     <map:transform src="stylesheets/xhtml/lorien/mux.xsl"/>
     </map:otherwise>
    </map:select>
    <map:serialize type="xhtml"/>
   </map:match>

It does not work and I have no real clue how to use theese components - though I have read the session context manual.

Cheers,
Jan