WMS_client image format problems

[K. Lessing]

Dear List,

I am running MapServer 4.2.3 at least with WMS_client capabilities.
I try to capture one layer "laender" out from www.geoway.de.
The whole bundle of layers can be seen here:
http://www.geoway.de/cgi-bin/mapserv3.cgi?MAP=/home/geoway/geoway.map&VERSION=1.1.0&REQUEST=GetMap&&SRS=EPSG:32632&BBOX=280450,5236000,921400,6102500

The geoway MapServer seams to produce images which are stored in my
directory:
/srv/www/htdocs/tmp/

Unfortunally the suffix of the files which are stored in my directory
and which my MapServer is trying to display are looking strange:
*.img.tmp

Does anybody know if  I configured something wrong?
(My Mapfile in the following)

best regards and
many thanx beforehand
Karsten


MAP

  NAME Testfile
  SHAPEPATH "../daten"
  SYMBOLSET "../docs/symbol.txt"
  FONTSET "/srv/www/htdocs/fonts/fonts.txt"
  EXTENT 280460 5235969 921383 6102410
  STATUS ON
  SIZE 400 400

  WEB
    TEMPLATE  "temp0.html"
    IMAGEPATH "/srv/www/htdocs/tmp/"
    IMAGEURL "/tmp/"
  END

  PROJECTION
    "init=EPSG:32632"
  END

  OUTPUTFORMAT
    NAME "Farbenfroh"
    DRIVER "GD/png"
    MIMETYPE "image/png"
    IMAGEMODE RGB
    EXTENSION "png"
  END

  LAYER
    NAME "laender"
    TYPE VECTOR
    STATUS DEFAULT
    CONNECTION "http://www.geoway.de/cgi-bin/geoway.map?"
    CONNECTIONTYPE WMS
    METADATA
      "wms_srs"             "EPSG:32632"
      "wms_name"            "laender"
      "wms_server_version"  "1.1.0"
      "wms_formatlist"      "image/png"
      "wms_format"          "image/png"
    END
  END

END