[Solved] ASP.Net MVC Error: not all code paths reurn a value

In below MVC code i am getting error please help me to fix it.

'DefaultController.Reg(medi_Reg)': not all code paths reurn a value

namespace MPIS_MVC.Controllers
{
    public class DefaultController : Controller
    {
        //// GET: Default        
        private StudentEntities dc = new StudentEntities();

        //registration Action
        [HttpGet]
        public ActionResult reg()
        {
            return View();
        }

        //reg post action
        [HttpPost]
        [ValidateAntiForgeryToken]
        public ActionResult Reg([Bind(Include = "Id,fname,lname,Username,password,address,contact,mailid")] medi_reg medi_Reg)
        {
            if (ModelState.IsValid)
            {
                using (StudentEntities dc = new StudentEntities())
                {
                    dc.medi_reg.Add(medi_Reg);

                    dc.SaveChanges();
                    //  return RedirectToAction("reg");
                }

                return View(medi_Reg);
            }
            else
            {

            }
        }
    }
}