I am using OpenLayers in Drupal to display Geoserver WMS data. I can get the layer to overly properly, however the raster layer (png) has a white background I cannot remove. I have created a style in Geoserver using: ... FeatureTypeStyle - Rule - RasterSymbolizer - ColorMap - ColorMapEntry
However, even though this style is referenced in the 'Styles' for the OpenLayers layer in Drupal, nothing I do to this style file makes any changes to the map. ie: the background is always white. I have also tried to use opacity to make the entire layer transparent, but nothing changes. Drupal does not seem to be applying the style to the layer.
I am not sure if it matters, but the Geoserver information is provided by an external WMS server: http://nowcoast.noaa.gov/wms/com.esri.wms.Esrimap/obs?service=wms&version=1.1.1&request=GetCapabilities
Has anybody had this problem and found the proper fix?