hi, i have following selectlist for dropdownbox in aspnet mvc.

This is the editEmployee Action controller, so while edit page is displayed i want to display a selectvalue in dropdownbox,since "SelectList" takes 3 parameters one for value,one for text and other is for selected value, here i'm not getting what should i pass in 3rd parameter, coz its asking an object for selected value.

ViewData["DepartmentList"] = new SelectList(DepartmentRepository.GetDepartmentsBySchoolIdInList(ViewData["schoolId"].ToString()),"DepartmentId","DepartmentTitle");

here is the view

=Html.DropDownList("DepartmentList")