Why do I get these errors in my module?
Drupal forms should be called using the drupal_get_form() method, even from menu callbacks. Your menu item needs to look like this:

$items['myform/data_entry_form'] = array(
  'type' =&gt; MENU_CALLBACK,
  'access arguments' =&gt; array('access content'),
  'page callback' =&gt; 'drupal_get_form',
  'page arguments' =&gt; array('myform_data_entry_form') 
);

return $items;


Make sure you clear Drupal's caches each time you make a change in hook_menu(), otherwise it won't get picked up.