a request.SetAttribut in a Flowscript to the sitemap request-param doesn't work

[Nicolas Maisonneuve <n....@hotpop.com>]

hy,
i try to transform a uploaded xml file 
i write this flowscript to upload 

function upload() {
    var role = Packages.lab.crip5.ECR.cocoon.components.FileUploadManager.ROLE;
     var uploader=   cocoon.getComponent(role);
     var part = cocoon.request.get("description");
     uploader.setUploadFolder("c:/");
     var filename = uploader.upload(part); 
     cocoon.request.setAttribute("uploadedfile", filename);
     cocoon.sendPage("description.save");
}
the upload work !

and in my sitemap , i have this

<map:match pattern="upload.do">
    <map:call function="upload"/>
   </map:match>

    <map:match pattern="description.save">
         <map:generate src="{request-param:uploadedfile}"/>
          <map:serialize type="xml"/>
       </map:match>

but the {request-param:uploadedfile} is null 

how send a parameter in the sitemap ?