Fatal error(Call to a member function quoteIdentifier() on a non-object), on batchUpdateIndex(), file search.php on line 246

I am creating a search in such a way that's:
$tenders = Doctrine::getTable('TableTenders');
$tenders->batchUpdateIndex();

after excute i have fatal error: Fatal error: Call to a member function quoteIdentifier() on a non-object in E:\home\tender.loc\www\engine\class\Doctrine\Doctrine\Search.php on line 246

When i am opened Search.php on 246 line, i saw : $conn->quoteIdentifier($this->_table->getTableName())

var_dump($conn) return NULL

I climbed up the code and saw the error: $conn = $this->_options['connection']; (line 228)
i change this on $conn = $this->_options['table']->getConnection();

now works fine

Sory for my english