Doctrine - PHP Fatal error: 'Couldn't get last insert identifier.'

I'm having a little issue with Doctrine. Im getting the following error:

PHP Fatal error:  Uncaught exception 'Doctrine_Connection_Exception' with message 'Couldn't get last insert identifier.'

I looked at this post, Doctrine Problem: Couldn't get last insert identifier, which was helpful but my problem is a little different.

I'm getting this error on a table that is NOT supposed to have an auto_increment primar开发者_运维技巧y key. My setup is as follows:

Event:
  id:int, PK, auto_increment

User
  id: int, PK, auto_increment

UserEvent:
  user_id:int, PK
  event_id: int, PK

I'm having the issue on the insert into the UserEvent. So the flow is, I insert a record into Event, I then insert a record into User, and then I insert a record into UserEvent.

The funny part is, it inserts all 3 of these fine. But after inserting the last one (UserEvent) it throws that error.

Any ideas?

Figured it out -- in the YML schema, UserEvent.user_id and UserEvent.event_id did not have the attribute - primary: true

Once I did that and re-generated the models, the error went away