Update In LINQ not Working

Problem: I am working on a console application and I have a table in my .DBML File as FirstTable

I am using following code written below to update a field "Father Name" but it is still not updating it in Relational Database MS SQL.

VB Code:

Imports System.Data
Imports System.Collections.Generic
Module Module2
    Dim DB As New NorthWinddatacontext()

    Sub main()

        Dim UpdateName = (From p In DB.FirstTables Where p.Name = "Yousuf"
                       Select p).Single

        UpdateName.FatherName = "Hashmi1"
        DB.SubmitChanges()
    End Sub

My code is not working

Solution: You have not set any Primary Key on Your Table  in your Relational Database.Make a Primary Key and try the same code again by Droping the table again on Your DBML.