problem invoking WCS: "no template"???

[Jeff de La Beaujardiere]

I am trying to make the Web Coverage Service (WCS) feature work.
However, GetCapabilies and GetCoverage requests both respond with
"mapserv(): Web application error. No template provided."
No doubt I have made some basic configuration error, but I cannot
find my problem. The Web Map Service (WMS) functionality using
the same mapfile does work.

Here are the parts of my mapfile that I believe are relevant to WCS:

# Added for WCS support
OUTPUTFORMAT
   NAME GEOTIFF
   DRIVER "GDAL/GTiff"
   MIMETYPE "image/tiff"
   IMAGEMODE "BYTE"
   EXTENSION "tif"
END

   # TEST WCS feature
   LAYER
     NAME "airstiff"
     TYPE RASTER
     DUMP TRUE
     METADATA
       "wcs_title" "AIRS TIFF Coverage"
       "wcs_nativeformat" "tiff"
     END
     STATUS off
     PROJECTION
       "init=epsg:4326"
     END
     DATA "/sivo/data/soar/airs/2007/01/04/12/bt.tiff"
   END

NOTE: The same floating-point GeoTIFF (bt.tiff) is correctly
read and classified by the WMS component.

Is there something missing in my mapfile? This document:
http://mapserver.gis.umn.edu/docs/howto/wcs_server/#d45e65
claims that four conditions must be satisfied, as I
believe I have done:
       Data source is of raster type that is processed using GDAL (e.g GeoTIFF, Erdas Imagine, ...)
       LAYER NAME must be set
       LAYER TYPE is RASTER
       LAYER DUMP parameter set to TRUE

Thanks for any help,
Jeff DLB