msAccess2007 &c# error:" There is no row at position 0

Question

sir, I followed ur good instructions on "how to connect MsAccess2007 with C#. I have created my database named Document, dataset named Docs.... I used 7 controls( 4,a comboBox and 2 dateTimePicker. I carefully wrote the program just like yours. But at run time....it throws an error of "There is no row at position 0", and therefore will not load the page. Pls it is worrisome. What can I do, or what am I doing wrong. I had even populated a row in the database(Documents.accdb), but still the "error"remains.