I created 3 doctrine entities: 

* [Inquiry (has many Questions)](http://pastebin.com/Cdh57Yqp),
* [Question (has many Answers)](http://pastebin.com/WZwzzG2q),
* [Answer](http://pastebin.com/d31bV5a9).

Everything works well until I try to add ANY "answer", then I get a PDOException:

```
[PDOException]  
SQLSTATE[23000]:
Integrity constraint violation: 
1452 Cannot add or update a child row: 
a foreign key constraint fails 
(`ankieter`.`answer`, CONSTRAINT `FK_DD714F131E27F6BF` FOREIGN KEY (`question_id`) REFERENCES `Question` (`id`)) 

```

[Fixture code for testing](http://pastebin.com/LL2x0tsK)

[The error I get](http://pastebin.com/PTKjkNF3)

**EDIT:**
When I export my DB structure with PhpMyAdmin, delete information about foreign keys and import the structure back, everything works well (I am able to add data to "Answer" table).
What could be wrong with the foreign keys?