Cannot implicitly convert type 'System.Collections.Generic.List<AnonymousType#1> in C#

Hi I'm new to programming, could you please help me with this one:

I'am getting an error in "To.List()" Error 1 Cannot implicitly convert type 'System.Collections.Generic.List' to 'System.Collections.Generic.List

My Code is:

List<IncByYrMonthModel> GroupedList = (from p in incidentsViewModel
                                       group p by new 
                                       { 
                                           month = p.DateClosed.Value.Month, 
                                           year = p.DateClosed.Value.Year 
                                       } into d
                                       select new 
                                       {
                                           d.Key.month, 
                                           d.Key.year, 
                                           count = d.Count() 
                                        }).ToList();
return GroupedList;

My Model is:

public class IncByYrMonthModel
{
    public string Year { get; set; }
    public string Month { get; set; }
    public string Total { get; set; }
}

Updated code

public List<IncByYrMonthModel> GetYrMonth2(HttpSessionStateBase session, int id, int _StrYear)
{
    List<IncidentsModel> incidentsViewModel = ViewModelService.Fetch<List<IncidentsModel>>(session, id);

    List<IncByYrMonthModel> GroupedList = (from p in incidentsViewModel
                                           group p by new 
                                           { 
                                               month = p.DateClosed.Value.Month, 
                                               year = p.DateClosed.Value.Year 
                                            } into d
                                            select new IncByYrMonthModel 
                                            { 
                                                Month = d.Key.month, 
                                                Year = d.Key.year, 
                                                Total = d.Count() 
                                            });

        return GroupedList;
    }