title: Error messages not working on one model, when validation fails
body: <p>I have a form that calls on two separate models.  My validation works correctly in that incorrectly entered data fails validation; however, the error messages only show on the RELATED model data.  Here is a snippet of my form with both models:</p>
  
  <pre><code>echo $this-&gt;Form-&gt;input('Location.exchange', array('size'=&gt;'3', 'error' =&gt; array('class' =&gt; 'error')));
  echo $this-&gt;Form-&gt;input('Location.sln', array('size'=&gt;'4', 'error' =&gt; array('class' =&gt; 'error')));
  echo '&lt;br /&gt;';
  echo $this-&gt;Form-&gt;input('unit_website', array('size'=&gt;'65', 'label'=&gt;'Your unit\'s website', 'error' =&gt; array('class' =&gt; 'error')));
  echo '&lt;br /&gt;';
  
  echo $this-&gt;Form-&gt;input('specials', array('size'=&gt;'65', 'label'=&gt;'Your website\'s Specials page', 'error' =&gt; array('class' =&gt; 'error')));
  echo '&lt;br /&gt;';
  </code></pre>
  
  <p>Error messages will be display whenever validation fails on Location, but not the other (which is Unit), which is ironic, since I'm in my UnitsController.  Here is the controller code:</p>
  
  <pre><code>function edit($id) {
   $this-&gt;set('title', 'Edit your property');
   $this-&gt;Unit-&gt;id = $id;    
   if (empty($this-&gt;request-&gt;data)) {        
  $this-&gt;request-&gt;data = $this-&gt;Unit-&gt;read();    
  } else { 
  
      if ($this-&gt;Unit-&gt;saveAll($this-&gt;request-&gt;data)) {            
          $this-&gt;Session-&gt;setFlash('Your property has been updated.', 'success');            
      } else {
          Set::merge($this-&gt;Unit-&gt;read(), $this-&gt;request-&gt;data);
      } 
  }
  }
  </code></pre>
  
  <p>and here is a snippet of the validation arrays from both my Location model and my Unit model:
    (from model Unit):</p>
  
  <pre><code>public $validate=array(
      'type'=&gt;array(
          'rule'=&gt;'notEmpty',
          'message'=&gt;'You must choose what type of property this is.'
      ),
      'unitnum'=&gt;array(
          'rule'=&gt;array('custom', '/^[a-z0-9 -\'.\/&amp;]*$/i'),
          'message'=&gt;'Must be the name or number of your unit.'
      )
   );
  </code></pre>
  
  <p>(from model Location):</p>
  
  <pre><code>public $validate = array(
          'area_code'=&gt; array(
              'ac1'=&gt; array(
                  'rule'=&gt;'numeric',
                  'message'=&gt;'Must be a number'
              ),
              'ac2'=&gt;array(
                  'rule'=&gt;array('comparison', '&gt;=',100),
                  'message'=&gt;'You must enter a valid area code'
              )
       );
  </code></pre>