Object reference not set to an instance of an object error

hey guys, i met up with this error when im trying to update the row in gridview.

Object reference not set to an instance of an object. Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

Source Error:






Line 197: Dim ClsTickets_Obj As New clsTickets
Line 198: ClsTickets_Obj.Reasons = tbReasons.Text
Line 199: ClsTickets_Obj.DBUpdate(Convert.ToInt16(Hidden_ID.Value))
Line 200: GridViewListTicket. ...