Problems with tween class of flash? Solution Tweener

I just came around something crazy in Flex, it happened before but i just forgot about it. I made a datagrid inside a custom component and used the creationComlete to call an init function. In that init function i set the dataprovider property to an ArrayCollection (defined in a singleton). In this case the databinding was not working, when i changed my code to following: <mx:DataGrid id="dgrCourses" dataProvider="{BackendModel.getInstance().info.courseList}"/> everything works fine.