Sql command

System.Data.OleDb.OleDbException: "Ошибка синтаксиса в инструкции INSERT INTO."

 using (var connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:/Users/user/Desktop/VetRegistration/VetClinic.mdb"))
            {
                connection.Open();
                OleDbCommand command = new OleDbCommand();
                command.Connection = connection;
                System.Windows.Forms.Form Form3ClientName = System.Windows.Forms.Application.OpenForms["Form3"];
                string s1 = ((Form3)Form3ClientName).textBox1.Text;
                string s2 = comboBox1.DisplayMember;
                string s3 = dateTimePicker1.Value.ToString();
                
                command.CommandText = "insert into Registration(Owner, Doctor, Time) values('" + s1 + "', '" + s2 + "', '" + s3 + "')";
                label3.Text = command.CommandText;
                OleDbCommand comm = new OleDbCommand(command.CommandText, connection);
 
                command.ExecuteNonQuery();
            }

using (var connection = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:/Users/user/Desktop/VetRegistration/VetClinic.mdb"))
            {
                connection.Open();
                OleDbCommand command1 = new OleDbCommand();
                command1.Connection = connection;
                string s1 = textBox1.Text;
                string s2 = textBox2.Text;
                string s3 = textBox3.Text;
                command1.CommandText = "insert into Client(Owner, PetName, Type) values('" + s1 + "', '" + s2 + "', '" + s3 + "')";
                OleDbCommand comm = new OleDbCommand(command1.CommandText, connection);
                label4.Text = command1.CommandText;
                command1.ExecuteNonQuery();
            }

                string sql = "insert into Registration(Owner, Doctor, [Time]) values(@o, @d, @t)"; // Для MS SQL/Access
                // string sql = "insert into Registration(`Owner`, `Doctor`, `Time`) values(@o, @d, @t)"; // Для MySQL
                OleDbCommand comm = new OleDbCommand(sql, connection);
                comm.Parameters.AddWithValue("@o", ((Form3)Form3ClientName).textBox1.Text);
                comm.Parameters.AddWithValue("@d", comboBox1.DisplayMember);
                comm.Parameters.AddWithValue("@t", dateTimePicker1.Value);
                command.ExecuteNonQuery();

public void CreateMyOleDbCommand(OleDbConnection connection,
    string queryString, OleDbParameter[] parameters)
{
    OleDbCommand command = new OleDbCommand(queryString, connection);
    command.CommandText =
        "SELECT CustomerID, CompanyName FROM Customers WHERE Country = ? AND City = ?";
    command.Parameters.Add(parameters);
 
    for (int j=0; j<parameters.Length; j++)
    {
        command.Parameters.Add(parameters[j]) ;
    }
 
    string message = "";
    for (int i = 0; i < command.Parameters.Count; i++)
    {
        message += command.Parameters[i].ToString() + "\n";
    }
    Console.WriteLine(message);
}