input string not in currect format

Question

DivisionInfo infodivision = new DivisionInfo();
                infodivision.classId = decimal.Parse(DropDownList1.SelectedValue.ToString());
                infodivision.divisionName = TxtdivisionName.Text;
                DivisionSp spdivision = new DivisionSp();
                spdivision.divisionAdd(infodivision);
                gridfill();
                clear();