Symfony2 Doctrine OneToMany Error - php

Question

I have a big understanding problem with OneToMany Relationship - i searched a lot but that didnt help, maybe someone can help me with this.
I have a Event Entity with OneToMany Relation
<?php
namespace #\#\#;
use Doctrine\Common\Collections\ArrayCollection;
use Doctrine\ORM\Mapping as ORM;
use Turmforum\BookingBundle\Entity\Contact;
/**
* Event
*
* #ORM\Table(name="events")
* #ORM\Entity
*/
class Event
{
/**
* #var integer
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #ORM\OneToMany(targetEntity="Contact", mappedBy="event")
*/
protected $event_contacts;
/**
*
*/
public function __construct() {
$this->contacts = new ArrayCollection();
}
/**
* Get id
*
* #return integer
*/
public function getId()
{
return $this->id;
}
public function getContacts() {
return $this->contacts;
}
public function addContact(Contact $contact) {
$this->contacts[] = $contact;
return $this;
}
And have a Contact Entity with ManyToOne Relation
<?php
namespace #\#\#;
use Doctrine\ORM\Mapping as ORM;
use Turmforum\BookingBundle\Entity\Event;
/**
* Contact
*
* #ORM\Table(name="contacts")
* #ORM\Entity
*/
class Contact
{
/**
* #var integer
*
* #ORM\Column(name="id", type="integer")
* #ORM\Id
* #ORM\GeneratedValue(strategy="AUTO")
*/
private $id;
/**
* #ORM\ManyToOne(targetEntity="Event", inversedBy="event_contacts")
* #ORM\JoinColumn(name="event_id", referencedColumnName="id")
*/
protected $event;
/**
* Get id
*
* #return integer
*/
public function getId()
{
return $this->id;
}
/**
* #return mixed
*/
public function getEvent() {
return $this->event;
}
When i try to save my event details over a form i get the error:
Neither the property "event_id" nor one of the methods "getEventId()",
"eventId()", "isEventId()", "hasEventId()", "__get()" exist and have
public access in class "Turmforum\BookingBundle\Entity\Event".
What am i missing?