data not inserting in service based database in win form

hello all i am working on window application with local (service based database ) database. but while i am inserting with this than no data insert into nor showing any error . but when connect with external sql server its working well.

 SqlConnection con = new SqlConnection(@"Data Source=.\SQLEXPRESS;AttachDbFilename=|DataDirectory|\Database1.mdf;Integrated Security=True;User Instance=True");
            using (var cmd = new SqlCommand("insert student (Id,Name,mobile,city) values (@Id,@Name,@mobile,@city)", con))
            {


                cmd.Parameters.AddWithValue("Id", 126262);
                cmd.Parameters.AddWithValue("@Name", "manebde");
                cmd.Parameters.AddWithValue("@mobile", 33333);
                cmd.Parameters.AddWithValue("@city", "ss");
                con.Open();
                cmd.ExecuteNonQuery();
                con.Close();
                MessageBox.Show("data saved");
            }