primitive type error in linq query

Question

public ActionResult CaseVolumeByTypeChartGraph()
{
MPOWERINGDBContext db = new MPOWERINGDBContext();
db.Configuration.ProxyCreationEnabled = false;
int ID = Convert.ToInt32(Session["UserId"]);
List mycompany = db.Companies.ToList();
List payr = db.Payers.ToList();
List cases = db.Cases.ToList();
List ptnt = db.Patients.ToList();
var multipletable = (from s in mycompany where s.UserID == ID select s).ToList();
//var query = db.Cases.Include("Patient")
var query = db.Cases.Include("Patient")
.Where(x => (mycompany.Select(y => y.CompanyID)).ToList()
.Contains(x.CompanyID ?? 0))
.GroupBy(p => new { p.DateOfService })
.Select(g => new CompanyUserViewModel
{
mydate = (DateTime)g.Key.DateOfService,
Eligiblechart = g.Count(w => w.Patient.InsuranceType == "Eligible"),
Otherchart = g.Count(w => w.Patient.InsuranceType == "Other")
}).ToList();

Please anyone tell me why query not execute and return show 

 

Unable to create a constant value of type 'MPOWERING.Models.DB.Company'. Only primitive types or enumeration types are supported in this context.