Enitity FrameWork 4.1 is not adding any row to database SQLExpress .
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Working with Entity Framewirk 4.1 with SQL Express MDF Database .

for test purpose i am trying to perform CRUD operations on SQL Express Database using Enitity Model in WPF Application .
 
I am new to this concept , and i followed the video Tut and done coding according that 

I created Entity model of single very simple table . and wrote simple code in cs file to f\perform adding one row to the database using following code 

    testEntities db = new testEntities();
        TestTable tb = new TestTable();
        tb.Name=txtName.Text;
        tb.Email = txtMail.Text;
        db.TestTables.AddObject(tb);
        db.SaveChanges();

 but if i go back check the database no data is added .  please tell me whats going wrong here ??
