CodeIgniter 和 Doctrine 插入数据'持久化'异常

大家好,如题...........请帮帮忙.................

代码-->
class User extends Doctrine_Record {
    public function setTableDefinition(){
        $this->hasColumn('username','string',255);
        $this->hasColumn('password','string',255);
        $this->hasColumn('first_name','string',255);
        $this->hasColumn('last_name','string',255);
    }
}
---------------------------------------------------
代码-->
class Hello extends Controller {
    function index(){
        //储存第一个对象
        $user1=new User();
        $user1->username='jack';
        $user1->password='123456';
        $user1->first_name='chen';
        $user1->last_name='fuck';
        $user1->save();
    }
}
--------------------------------------------
异常->

Fatal error: Uncaught exception 'Doctrine_Transaction_Exception' with message 'Rollback failed.  
There is no active transaction.' in  
C:\AppServ\www\CodeIgniter\system\application\plugins\doctrine\lib\Doctrine\Transaction.php:319  
Stack trace: #0  
C:\AppServ\www\CodeIgniter\system\application\plugins\doctrine\lib\Doctrine\Connection.php(1426):  
Doctrine_Transaction->rollback(NULL) #1  
C:\AppServ\www\CodeIgniter\system\application\plugins\doctrine\lib\Doctrine\Connection\UnitOfWork.ph
p(136): Doctrine_Connection->rollback() #2  
C:\AppServ\www\CodeIgniter\system\application\plugins\doctrine\lib\Doctrine\Record.php(1599):  
Doctrine_Connection_UnitOfWork->saveGraph(Object(User)) #3  
C:\AppServ\www\CodeIgniter\system\application\controllers\hello.php(18): Doctrine_Record->save() #4  
[internal function]: Hello->index() #5  
C:\AppServ\www\CodeIgniter\system\codeigniter\CodeIgniter.php(236): call_user_func_array(Array,  
Array) #6 C:\AppServ\www\CodeIgniter\index.php(115): require_once('C:\AppServ\www\...') #7 {main}  
thrown in  
C:\AppServ\www\CodeIgniter\system\application\plugins\doctrine\lib\Doctrine\Transaction.php on line  
319