Poster nog showing

When I add a poster to the video because I don’t want a black screen before playing, it doesn’t show. This is the code I used: [video src="/wp-content/uploads/2013/01/Adelinde_Instructievideo_promoklein.mov" width="300" height="170" poster="http://www.adelindetrainingcenter.nl/wp-content/uploads/2012/12/adelinde-en-tjalling-480x270.jpg"]

Hopefully someone can help me fix this problem 🙂

http://wordpress.org/extend/plugins/media-element-html5-video-and-audio-player/