Theming Node Edit Forms
In your template.php the hook_theme implementation should look like that:

function dupublic_theme($existing, $type, $theme, $path) {
  return array(
    'page_node_form' =&gt; array(
      'template' =&gt; 'page-node-form',
      'render element' =&gt; 'form',
    ),
  );
}


Notice that in the return array 'render element' key is without underscore, and there is no 'arguments' key in Drupal 7 version of hook_theme(). It is replaced by 'variables' key, but the documentation states that:


  Each information array must contain either a 'variables' element or a
  'render element' element, but not both. Use 'render element' if you
  are theming a single element or element tree composed of elements,
  such as a form array, a page array, or a single checkbox element.


Another point that I notice is, that you used in your page-node-form.tpl.php file statements like:

&lt;?php print drupal_render($form['title']);?&gt;


I prefer to print the elements like that, and recommend you to do so:

&lt;?php print render($form['title']);?&gt;


It's a new function in Drupal 7 and it calls drupal_render() but first checks if the passed element is an array and also calls show() function if the element is set hidden.