gridview does not update changes in dataset

I have a listbox and a gridview which are bounded to a typed dataset created by visual studios design-time support. When I add a row to the dataset in code the listbox updates the changes without any problems, but the datagridview does not. Is there anything I misunderstood. I thought any changes made to the dataset are detected by the connected bindingsource and than reflected automatically in the user interface.

thx for any help