This is more suited to the OpenLayers list, but at a guess it's because of an incorrect maxResolution setting on the WMS layer, they default to the Map, or if that's not set, auto-generated not always successfully.
Setting up the Map object as shown here should be the first step to getting the overlay to display. http://wiki.openstreetmap.org/wiki/OpenLayers_Simple_Example#Instructions 2009/3/30 Andrew Ayre <a...@britishideas.com>: > Hi! I am generating a map using OpenLayers with an OSM base map and a > WMS overlay. At the backend I am running GeoServer 1.7.3 with PostGIS. > > I can view my WMS data fine in the client in GeoServer and in uDig. > However when I overlay it on my OpenLayers map it disappears at nearly > all the zoom levels. Here is a demo: > > http://www.britishideas.com/osm > > When you load this you can see a black dot over southern Arizona. This > is my overlay. When you zoom in it disappears. > > Any ideas what I am doing wrong? > > thanks, Andy > > -- > Andy > PGP Key ID: 0xDC1B5864 > > _______________________________________________ > dev mailing list > dev@openstreetmap.org > http://lists.openstreetmap.org/listinfo/dev > -- Regards, Thomas Wood (Edgemaster) _______________________________________________ dev mailing list dev@openstreetmap.org http://lists.openstreetmap.org/listinfo/dev