Invalid parameter number with prepare method on query

  $query = $modx->newQuery('Tariff');

  $query->where("(`tariff`.`property` = :prop) AND ((`tariff`.`date_from` between :from AND :to ) OR ( `tariff`.`date_to` between :from AND :to ))");

  $query->prepare(array(
    'prop' => array('value' => 1, 'type' => PDO::PARAM_INT),
    'from' => array('value' => '2011-01-01', 'type' => PDO::PARAM_STR),
    'to' => array('value' => '2011-12-31', 'type' => PDO::PARAM_STR)
  ));

PHP warning: PDOStatement::execute() [<a href='pdostatement.execute'>pdostatement.execute</a>]: SQLSTATE[HY093]: Invalid parameter number: no parameters were bound
[2011-01-19 01:07:08] (ERROR @ /index.php) Error HY093 executing statement: 
Array
(
    [0] => HY093
)