WMS issue and MapGuide help

I am trying to load map using wms service.

var imageryLayers = viewer.imageryLayers;
imageryLayers.addImageryProvider(new Cesium.WebMapServiceImageryProvider({
url : '..../ArcGIS/services/Specialty/[service-name]/MapServer/WMSServer?REQUEST=GetCapabilities...',
layers : '0,4,5,6'
Only black tiles/images are loading, no map is shown. 
If I use same [servce-name] for ArcGisMapServerImageryProvider on same server, maps does get load.
I actually want to use an open source service MapGuide. I think if I can use ArcGIS wms service, then I will be able to shift to MapGuide's wms service.
Can you suggest me a better soluiton on that?


Try leaving off the query part of the URL (everything after ?REQUEST=…).