Asp.Net Silverlight Media and Xaml control

[Oriane]

Bonjour,

With Asp.Net futures (Microsoft.Web.Preview), I can't use the Media and Xaml
controls (Silverlight). I've got this error messages, with several wmv
files:

Execution error:

Microsoft JScript: Sys.Preview.UI.Xaml.Media.MediaFailedException: Unable to
load media "App_Data/xxx.wmv".

function Sys$Preview$UI$Xaml$Media$Player$_meMediaFailed() {
this._naturalduration = null;
this._enableBuffering(false);
this._mediaAvailable(false);
this._ensureDuration(false);
this._ensureSeeking(false);
this._mediaEnded = false;
this.set_caption("");

var handler = this.get_events().getHandler('mediaFailed');
if (handler) {
handler(this, Sys.EventArgs.Empty);
}
else {
throw this._getMediaFailedError(); <------
}
}

Any idea ?
Oriane