validate binding data

My TextBox binds to a field of a Dataset. Type of the field is double. When I enter a data in the TextBox ( not a double, for example string ) then my data is lost and TextBox sets a previous data. This event occurs till the validating event. How can I set off this automatic binding check. If I set CausesValidation to false then a validating event doesn’t occur, but I need this event. I think to rebind my textBox is not a very good idea. Does anybody khow how I can decide this problem . Maybe somebody will give me links to some articles.