Unable to insert data in MS Access using parameterized query in c#

Question

I have the following code which tries to store e values form 3 textboxes into a MS Access 2007 database.

string ConnString = (@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=|DataDirectory|\\dxs.accdb");
string SqlString = "Insert Into tests( [Nam], [add], [phone]) Values (?,?,?)";

using (OleDbConnection conn = new OleDbConnection(ConnString))
{
   using (OleDbCommand cmd = new OleDbCommand(SqlString, conn))
   {
      cmd.CommandType = CommandType.Text;
      cmd.Parameters.AddWithValue(@"Nam", textBox1.Text);
      cmd.Parameters.AddWithValue(@"add", textBox2.Text);
      cmd.Parameters.AddWithValue(@"phone",textBox3.Text);

      conn.Open();
      cmd.ExecuteNonQuery();
      MessageBox.Show("entered");
   }
}

But even though the code is correct after entering values nothing is being stored in table.

Answer 1

Shouldn't

cmd.Parameters.AddWithValue(@"Nam", textBox1.Text);

Be:

cmd.Parameters.AddWithValue("@Nam", textBox1.Text);

And so on for the other parameters?