Data Controls :: Data Not Inserting In Service Based Database In Win Form?

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");
}