title: CakePHP: Validation message not showing but $this->validationErrors works
body: <p>I have a field <code>gentel_id</code> with the following validation rules in my model <code>Contrat</code>:</p>
  
  <pre><code>public $validate = array(
      'gentel_id' =&gt; array(
          'numeric' =&gt; array(
              'rule' =&gt; 'numeric',
              'required' =&gt; true,
              'allowEmpty' =&gt; false,
              'message' =&gt; 'Veuillez entrer un identifiant GENTEL ou mettre la valeur 0000000000',
          ),
      ),
  );
  </code></pre>
  
  <p>In my controller:</p>
  
  <pre><code>    public function add($id = null) { 
        if ($this-&gt;request-&gt;is('post')) {
  
        $this-&gt;Contrat-&gt;create();
  
        if ($this-&gt;Contrat-&gt;save($this-&gt;request-&gt;data)) {
  
          $this-&gt;Session-&gt;setFlash(__('Le Contrat a été ajouté'));
          $this-&gt;redirect(array('action' =&gt; 'edit', $this-&gt;Contrat-&gt;getInsertID() ));
        } else {
          debug($this-&gt;Contrat-&gt;validationErrors);
          $this-&gt;Session-&gt;setFlash(__('Le Contrat ne peut être ajouté'));
        }
      $this-&gt;set('id',$id);
      ...
      }
  </code></pre>
  
  <p>In my form:</p>
  
  <pre><code>    &lt;?php echo $this-&gt;Form-&gt;create('Contrat');?&gt;
              &lt;?php                           
                          if (empty($id)){
                              echo $this-&gt;Form-&gt;input('client_id',array('empty' =&gt; "Client non défini",'default' =&gt; $id, 'onchange'=&gt;"window.location.href= '/contrats/add/'+this.form.ContratClientId.options[this.form.ContratClientId.selectedIndex].value"));
                          }else{
                              echo "&lt;span class=\"label\"&gt;".__('Client')."&lt;/span&gt;".$this-&gt;Kaldom-&gt;link(h($clients[$id]),array('controller' =&gt; 'clients', 'action' =&gt; 'view',$id));
                              echo $this-&gt;Form-&gt;input('client_id', array('type' =&gt; 'hidden','value' =&gt; $id));
                          }
              echo $this-&gt;Form-&gt;input('gentel_id',array('type'=&gt;'text','label'=&gt; 'Gentel ID'));
                  ?&gt;
      &lt;?php echo $this-&gt;Form-&gt;end(__('Créer'));?&gt;
  </code></pre>
  
  <p>When I try to save my form with "gentel_id" empty, the save is correctly not done and a debug (<code>$this-&gt;Contrat-&gt;validationErrors</code>) give me this:</p>
  
  <pre><code>Array
  (
      [gentel_id] =&gt; Array
      (
          [0] =&gt; Veuillez entrer un identifiant GENTEL ou mettre la valeur 0000000000
      )
  
  )
  </code></pre>
  
  <p>But the error messsage is not displayed in my form.
  Note that it is an add function but I have passed a parameter in the url like this:
          .../contrats/add/3</p>
  
  <p>Can you help me please?</p>