Hello,
now, projector is working correctly.
It just have a default ratio.
I have tried different configuration for explain the problem.
You can see here :
http://www.fichier-pdf.fr/2011/02/02/issue-syphon-projector/
and if you want, you can download a small scene here :
http://www.megaupload.com/?d=T1AHCV3Y
Thank you for your help