Update Dataset from a Datagrid

[Gregory]

I have a problem with a datagrid. The user can edit and add new rows in a bound datagrid. I update the dataset binding to the datagrid when the current cell of the datagrid change. The problem is if the user change a value in a row without after move to an another rows of the datagrid, the dataset don't detect a change (and the update doesn't work). The dataset don't detect the changed on a row if we don't navigate on another row of the datagrid !! Have you the same problem ????? and a solution ? I hope you understand my bad english. Thank you