类型为’BioSheet.Models.BioSheetModel’的属性’Ward’上的ForeignKeyAttribute无效.在依赖类型“BioSheet.Models.BioSheetModel”上找不到外键名称“WardId”. Name值应该是以逗号分隔的外键属性名称列表.

public class Ward
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [ForeignKey("AddressId")]
    [required]
    public virtual Address WardAddress { get; set; }

    [ForeignKey("BioSheetId")]
    public virtual List<BioSheetModel> BioSheets { get; set; }

    [required]
    public String Code { get; set; }
}

public class BioSheetModel
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int Id { get; set; }

    [required]
    public String FirstName { get; set; }

    [required]
    public String LastName { get; set; }
    public String Email { get; set; }

    [ForeignKey("WardId")]
    [required]
    public Ward Ward { get; set; }

    public String CellPhoneNumber { get; set; }
    public String HouseNumber { get; set; }

    [required]
    public String DoB { get; set; }

    [required]
    public Address Address { get; set; }
    public String OtherInformation { get; set; }
    public String PrevIoUsCallings { get; set; }

    [ForeignKey("TimePeriodId")]
    public virtual TimePeriod TimePeriods { get; set; }
    public String HomeWard { get; set; }
    public Boolean OkToText { get; set; }

    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    [required]
    public DateTime TodaysDate { get; set; }

    [ForeignKey("EMPId")]
    public virtual EDUEMP EduEmp { get; set; }
    [ForeignKey("SingId")]
    public virtual Sing Singing { get; set; }

    [ForeignKey("MissionId")]
    public virtual Mission MissionIn { get; set; }
}

谁能帮我解决这个问题？