Brahim,
Do not double post (i.e. post in the Flex API forum and in the Flex Viewer forum) the same question. As this Question has to do with the Flex Viewer and a widget, I have merged your post from the Flex API with this one in the Viewer forum where it belongs.
If you want you threads answered then you need to spend time preparing your post and giving the apprpriate ammount of detail, i.e. xml configuration files, etc.