Geoserver point symbology with jpg, gif or png, not display in openlayer

Question

I would like to update graphic symbolize in geoserver style from svg to png, gif or jpg. However, the symbol doesn't display when I view in openlayer. Svg symbol works fine. Here is my code:

    <?xml version="1.0" encoding="UTF-8"?>
    <StyledLayerDescriptor xmlns="http://www.opengis.net/sld" xmlns:ogc="http://www.opengis.net/ogc" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="1.1.0" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.opengis.net/sld http://schemas.opengis.net/sld/1.1.0/StyledLayerDescriptor.xsd" xmlns:se="http://www.opengis.net/se">
  <NamedLayer>
    <se:Name>map_seed_source_site    </se:Name>
    <UserStyle>
      <se:Name>map_seed_source_site    </se:Name>
      <se:FeatureTypeStyle>
        <se:Rule>
          <se:Name>Single symbol    </se:Name>
          <se:PointSymbolizer>
            <se:Graphic>
              <se:ExternalGraphic>
                <se:OnlineResource xlink:type="simple" xlink:href="http://www.opendevelopmentcambodia.net/wp-content/themes/opendata/images/seed-sources-legend.gif" />
                <se:Format>image/gif</se:Format>
              </se:ExternalGraphic>
              <se:Size>100    </se:Size>
            </se:Graphic>
          </se:PointSymbolizer>
        </se:Rule>
      </se:FeatureTypeStyle>
    </UserStyle>
  </NamedLayer>
</StyledLayerDescriptor>

Answer 1

When you tried, have you also changed this line? from

<se:Format>image/gif</se:Format>

to

<se:Format>image/png</se:Format>

I'm also not sure if you can use <size> tag with non-vector graphic files. So try to change the gif to PNG and also to remove the size. The SLD will use the original size of the PNG. I'm not 100% sure it helps but it is worth a try...