C# libreoffice base connection

Question

i want make login form in c#. but i dont have access. and i cant use sql server . can you help me. why am i getting an error i make this code

        OdbcConnection con;
        OdbcCommand cmd;
        OdbcDataReader dr;
        private void button1_Click(object sender, EventArgs e)
        {
            string ad = textBox1.Text;
            string sifre = textBox2.Text;
            con = new OdbcConnection("Provider=Microsoft.ACE.Odbc.12.0;Data Source=dat.odb");
            cmd = new OdbcCommand();
            con.Open();
            cmd.Connection = con;
            cmd.CommandText = "SELECT * FROM kullan where ad='" + textBox1.Text + "' AND sifre='" + textBox2.Text + "'";
            dr = cmd.ExecuteReader();
            if (dr.Read())
            {
                Form2 f2 = new Form2();
                f2.Show();
            }
            else
            {
                MessageBox.Show("Kullanıcı adı ya da şifre yanlış");
            }

            con.Close();

        }