Silverlight error message

When trying to get a basic mms example working, I get this error:

"Silverlight error message
ErrorCode: 2203
ErrorType: RuntimeError
Message: AG_E_RUNTIME_SETVALUE
MethodName: Source"

With this Javascript:

<script type='text/javascript' src="embed/silverlight.js"></script>
<script type='text/javascript' src="embed/wmvplayer.js"></script>
<script type="text/javascript" src="embed/swfobject.js"></script>
<script type="text/javascript" src="embed/periboea.js"></script>
<script type="text/javascript">
var cnt = document.getElementById("container");
var src = 'embed/wmvplayer.xaml';
var cfg = {
height:'285',
width:'470',
file:'mms://wm3.streamzilla.jet-stream.nl/jet-stream/demostreams/goldfish_WMV_PAL.wmv',
//file:'video.wmv',
backcolor:'0x006666',
frontcolor:'0x333300',
usefullscreen:'false',
repeat:'true'
};
var ply = new jeroenwijering.Player(cnt,src,cfg);
</script>

Javascript error console displays this message also:
"Error: uncaught exception: Error setting property on scriptable plugin object! [plugin exception: AG_E_RUNTIME_SETVALUE : Source]."

Anyone have any ideas how to fix this? Or anyone get the same error?