Cakephp validation

PHP
1

In cakephp I am trying to check if an file input field has a file attached, and if not output an error. I have done this with other fields but just can’t seem to get this to work on that field.

Here is the model

<?php var $name = 'Upload';
	var $validate = array(
		'title' => array('notempty'),
		'uploadeduploaded_file' => array('notempty')
	);
?>

and here is my ctp file

<?php echo $form->input('Uploaded.uploaded_file', array('type' => 'file', 'label' => 'Upload file', "label" => false)); ?>

I am guessing that it must be something to do with what I should call the field in the model, but I have tried all sorts of combination’s and can’t get it work.

Any help would be grateful