It looks to me like the georss and gml namespace URIs that are provided by the RSS to GeoRSS converter are incorrect.
The following namespace declarations are included in the feeds:
xmlns:gml="http://www.opengis.net/gml/"
xmlns:georss="http://www.georss.org/georss/"
I believe that xml namespace declarations are intended to be compared using a strict string comparison, so these URIs would be considered different from the actual URIs provided in the GeoRSS/GML specifications: