Error in LINQ when work with PostGreSQL by Entity Framework

I have a problem with LINQ query. Here this:

List<a> get = (from i in entitiesFactory.subsDbContext.a
where i.id == id
select i).ToList<a>();

The model look like this"

public partial class a
    {        
        [Key]
        public int id { get; set; }

        [ForeignKey("contractors"), Column(Order = 0)]
        public Nullable<int> ot_contractor_id { get; set; }

        [ForeignKey("contractors1"), Column(Order = 1)]
        public Nullable<int> gvo_contractor_id { get; set; }

        public virtual contractors contractors { get; set; }
        public virtual contractors contractors1 { get; set; }    
    }

Table a look like this:

CREATE TABLE a
(
  id serial NOT NULL,

  ot_contractor_id integer,

  gvo_contractor_id integer,

  CONSTRAINT a_pkey PRIMARY KEY (nzp_thgf_det),

  CONSTRAINT a_gvo_contractor_id_fkey FOREIGN KEY (gvo_contractor_id)
      REFERENCES contractors (id) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION,

  CONSTRAINT a_ot_contractor_id_fkey FOREIGN KEY (ot_contractor_id)
      REFERENCES contractors (id) MATCH SIMPLE
      ON UPDATE NO ACTION ON DELETE NO ACTION,

)

So, table 'a' have 2 references to other table 'contractors'.

[a].[ot_contractor_id]  ---> [contractors].[id] 

and

[a].[gvo_contractor_id] ---> [contractors].[id].

The problem is: LINQ query has fallen when it try to execute.

ERROR: The column Extent1.contractors_id does not exist.