VS 2010 dataset bound to a datagridview

hi everyone,
when my dataset is bound to my datagridview and the autogeneratecolumns is set to true, any changes i made on the datagridview can be made to my database using objdataadapter.update.

but when i design my columns at run time and set autogeneratecolumns to false, the changes i made cannot be made back to the database.

Anyone can advise on this?

please do tell me to post the codes if necessary.

thanks a lot