c# - The Include path expression must refer to a navigation property defined on the type. -

  public int gethighestmarks(int classid, int examid, int subjectid)     {         list<examresult> examresultlist = null;         int highestmarks = 0;         try         {              basedatarepository<examresult> db = new basedatarepository<examresult>();             examresultlist = db.getlist(s => s.classid.equals(classid), e => e.examid.equals(examid), s => s.subjectid.equals(subjectid)).tolist();              if (examresultlist.count > 0)             {                 var markslistconsolidated = examresultlist                                         .groupby(e => e.subjectid)                                         .select(g => g.orderbydescending(e => e.marks).lastordefault())                                         .select(e => new                                         {                                                                                            e.marks,                                                                                 });                 highestmarks =convert.toint16((from e in markslistconsolidated                                                                       select e.marks));             }         }         catch (exception ex)         {             throw ex;         }         return highestmarks;     } 

i getting error in

examresultlist = db.getlist(s => s.classid.equals(classid), e => e.examid.equals(examid), s => s.subjectid.equals(subjectid)).tolist(); 

the error is:

[12:57 pm] sajjad hussain:

<<< examresultlist = db.getlist(s => s.classid.equals(classid), e => e.examid.equals(examid), s => s.subjectid.equals(subjectid)).tolist();sajjad hussain, today 12:57 pmye line me error araha hai niche wala

{"the include path expression must refer navigation property defined on type. use dotted paths reference navigation properties , select operator collection navigation properties.\r\nparameter name: path"}