gdal translate - gdal_translate KMLSUPEROVERLAY creates blank black image

I am trying to convert a geotiff to kmz file to view in GE. The geotiff is 878,720 KB. Using a 'regular kml' - the resolution is very low in GE. Having read around - it seems as conversion to a superoverlay is the best method?

I have chosen to use gdal_translate above other methods (e.g. MapTiler or Arc's tool that costs) because I have been using the GDAL python library already and I am trying to automate the entire process.

To test, I type into UNIX:

gdal_translate -of KMLSUPEROVERLAY filepath/2010_full_mosaic.tif filepath/2010_full_mosaic.kmz

A kml file is created....but on loading it into GE it is blank (black) - although extent/projection appear correct.

Would anyone be able to advise what I may have done wrong? When using the gdalinfo command, I am provided the following details:

Driver: GTiff/GeoTIFF
Files: Filepath/2010_full_mosaic.tif
       Filepath/2010_full_mosaic.tif.ovr
       Filepath/2010_full_mosaic.tif.aux.xml
Size is 10572, 22630
Coordinate System is:

PROJCS["WGS 84 / UTM zone 36S",
    GEOGCS["WGS 84",
         DATUM["WGS_1984",
            SPHEROID["WGS 84",6378137,298.257223563,
                AUTHORITY["EPSG","7030"]],
            AUTHORITY["EPSG","6326"]],
        PRIMEM["Greenwich",0],
        UNIT["degree",0.0174532925199433],
        AUTHORITY["EPSG","4326"]],
    PROJECTION["Transverse_Mercator"],

    PARAMETER["latitude_of_origin",0],
    PARAMETER["central_meridian",33],
    PARAMETER["scale_factor",0.9996],
    PARAMETER["false_easting",500000],
    PARAMETER["false_northing",10000000],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    AUTHORITY["EPSG","32736"]]
Origin = (390313.896406000014395,8164584.107470000162721)
Pixel Size = (25.000000000000000,-25.000624509551976)

Metadata:
  AREA_OR_POINT=Area
Image Structure Metadata:
  INTERLEAVE=BAND
Corner Coordinates:
Upper Left  (  390313.896, 8164584.107) ( 31d58'18.28"E, 16d35'54.43"S)
Lower Left  (  390313.896, 7598819.975) ( 31d56'22.37"E, 21d42'38.47"S)
Upper Right (  654613.896, 8164584.107) ( 34d26'57.65"E, 16d35'45.40"S)
Lower Right (  654613.896, 7598819.975) ( 34d29'41.00"E, 21d42'26.42"S)
Center      (  522463.896, 7881702.041) ( 33d12'49.09"E, 19d 9'27.96"S)

Band 1 Block=10572x1 Type=Float32, ColorInterp=Gray
 Overviews: 5286x11315, 2643x5658, 1322x2829, 661x1415, 331x708, 166x354

Becky