I don't see any obvious problems with the page. Sometimes this happens when the database has columns that are set to not allow null values and one or more of the fields is being passed in without a value.
To test that, update your orders database and allow null for all of the fields (except the autonumber of course) and try again. If one or more of the fields is inserted with a null value, that was the one causing the failure to insert when it wasn't allowed.