That code looks fine. I would say your problem is with your map service if nothing displays when you load your page. Are you able to view your service using the JavaScript preview from the services directory? The url should be http://servarcgisprd/arcgis/rest/services/Demo_001/MapServer?f=jsapi
Thank you so much for your response I do view the service using the JavaScript preview from the services directory...
Please, Any other ideas ?
Someone I work with said that the problem was the browser options in the in the "load images automatically" options but I'm not that sure about that...