Expanding the results view will enumerate the ienumerable."

I'm developing the master detail data entry form without using entityframwork. I have two tables deal making and deal details for this purpose and i have developed two model classes for master and detail and when I pass the values of master and detail to the controller using ajax call. its going well and all records are coming in the controller I check it by putting a breakpoint. but the issue is this it's not going inside while checking model state. It gives model state false and giving the error of " Results View = Expanding the Results View will enumerate the IEnumerable."

please help me as soon as possible

public JsonResult Create( ClsDealMaking clsDeal ) {
 if (ModelState.IsValid){
//error here  model state is false not understanding the reason
}

return Json(JsonRequestBehavior.AllowGet); }

public class ClsDealMaking
    {
        public int DealSysSeq { get; set; }
        public string DealCode { get; set; }
        public string DealName { get; set; }
        public DateTime ActiveFromDate { get; set; }
        public DateTime ActiveToDate { get; set; }
        public double TotalCost { get; set; }
        public double Discount { get; set; }
        public double Dealoffer { get; set; }
        public string Remarks { get; set; }
       // public Byte[] DealImage { get; set; }
        public virtual ICollection<clsDealDetail> DealDetails { get; set; }
    }