phpunit调用assertDataSetsEqual时出现致命错误

I am new to phpunit and kind of stuck in testing a database function with dbunit and getting the following error.

Fatal error: Cannot call constructor in C:\xampp\htdocs\testcases\PHPUnit\Extens ions\Database\Constraint\DataSetIsEqual.php on line 41

My test function is as follows.

public function testNewAccountCreation()
    {
        $bank_account = new BankAccount('12345678912345678', $this->pdo);
        $bank_account->addAccount();

        $expected = $this->createMySQLXMLDataSet(dirname(__FILE__).'/_files/bank-account-after-new-account.xml');

        $actual = new PHPUnit_Extensions_Database_DataSet_QueryDataSet($this->getConnection());
        $actual->addTable('bank_account');

        $this->assertDataSetsEqual($expected, $actual);
    }

I think the error is on calling assertDataSetsEqual function. Can any body please help me out with this problem on how to solve this error.

Thanks, Furqan Ahmed.