在MS Access数据库中插入数据

我的数据库在MS Access。我有一个名为Admin的表。它有两个属性Username和Password。当我使用插入查询插入数据时，它显示一条消息"insert INTO语句中的语法错误"，但我找不到问题。请帮助我的代码——

string cb = "INSERT INTO Admin(Username,Password) VALUES (@d1,@d2)";
command = new OleDbCommand(cb);
command.Connection = connection;
command.Parameters.Add(new OleDbParameter("@d1", System.Data.OleDb.OleDbType.VarChar, 20, "Username"));
command.Parameters.Add(new OleDbParameter("@d2", System.Data.OleDb.OleDbType.VarChar, 30, "Password"));

command.Parameters["@d1"].Value = textusername.Text;
command.Parameters["@d2"].Value = textpassword.Text;

command.ExecuteNonQuery();
MessageBox.Show("Successfully saved", "Student Details", MessageBoxButtons.OK, MessageBoxIcon.Information);
Add.Enabled = true;
if (connection.State == ConnectionState.Open)
{
    connection.Close();
}
connection.Close();