DataBase update on form changing

I have a form with a dataset in which the user adds data. If the user tries to close the form, I want to capture the changes made to the dataset (and havnt been written already to the table) and update the table accordingly. For some reason I cannot capture the changes made to the dataset. How do I do this? Here is my form closing event --> private void DivFrmClosing(object sender, System.ComponentModel.CancelEventArgs e) { ..... DataSet changedData = dataSet11.GetChanges(); if (changedData != null) dbUpdate(); // method which updates database ..... } changedData remains null even if I have uncommitted data in my dataset. Please help!!