flash movie with MAFileModel and SWFObject

Hi, I'm trying to render some uploaded files as flash movies... but without success by now... I thought it was easy, just putting this method in MAFileModel (and of course, changing #renderOn:): renderFlashOn: html html swfObject url: (self urlOn: html); with: 'Loading...'. But nothing happens (it shows "Movie not loaded...") If I put an "example" url, the example movie is loaded ok... :( renderFlashOn: html html swfObject url: 'http://www.mariaclaudiacortes.com/colors/Colors.swf'; with: 'Loading...'. So I think there is something in the URL generated by #urlOn: that is not good for swfObject (writing the html code directly drives to the same answer)... Any idea? Thanks, Esteban