How do I solve this problem :- escription: an error occurred during the parsing of a resource required to service this request.

asp:DropDownList ID="DropDownList1" runat="server">
            <asp:ListItem Value="0">Class</asp:ListItem>
            List<String>Sql.EmpoyerClasses= EmployerClassName</String>()
            ViewBag EmployerClasses= EmployerClassNameList(EmployerClasses);