[thredds] how to call WCS GetCoverage request?

Hi all,
I'm struggling with my first attempt to download a GeoTIFF using WCS from
TDS. I know this requires a GetCoverage request, but I get a "File not
found" error no matter what I've tried so far. GetCapabilities and
DescribeCoverage work, and I already have WCS allow=true and
allowRemote=true in threddsConfig.xml. The TDS logs do not say much of
anything. Is there something else I need to "turn on" before GetCoverage
will work?

GetCapabilities (works):

   -
   
http://oos.soest.hawaii.edu/thredds/wcs/pacioos/ncom/global/NCOM_Global_Ocean_Model_best.ncd?service=WCS&version=1.0.0&request=GetCapabilities


DescribeCoverage (works):

   -
   
http://oos.soest.hawaii.edu/thredds/wcs/pacioos/ncom/global/NCOM_Global_Ocean_Model_best.ncd?service=WCS&version=1.0.0&request=DescribeCoverage&coverage=water_temp


GetCoverage (all give "File not found" error):

   -
   
http://oos.soest.hawaii.edu/thredds/wcs/pacioos/ncom/global/NCOM_Global_Ocean_Model_best.ncd?service=WCS&version=1.0.0&request=GetCoverage&FORMAT=GeoTIFF&COVERAGE=water_temp&CRS=EPSG:4326&BBOX=127.529296875,-15.623036831528252,277.3828125,59.80063426102869&WIDTH=1705&HEIGHT=1034&TIME=2011-05-13T00:00:00Z&ELEVATION=0
   -
   
http://oos.soest.hawaii.edu/thredds/wcs/pacioos/ncom/global/NCOM_Global_Ocean_Model_best.ncd?service=WCS&version=1.0.0&request=GetCoverage
   -
   
http://oos.soest.hawaii.edu/thredds/wcs/pacioos/ncom/global/NCOM_Global_Ocean_Model_best.ncd?service=WCS

Ideas? Wrong syntax? A bug?
Thanks!,
John Maurer
Pacific Islands Ocean Observing System (PacIOOS)
University of Hawaii at Manoa