Form element is not rendered I am trying to render the form element below in telisim module but it's not working, no output (see the screenshot). 

The telisim.module file looks as follow:

//hook_menu

function telisim_menu() {
    $items['simcodes'] = array(
    'title' =&gt; 'SIM CODES',
    'page callback' =&gt; 'drupal_get_form',
    'page arguments' =&gt; array('telisim_examples'),
    'access callback' =&gt; TRUE,
    'type' =&gt; MENU_NORMAL_ITEM,
  );

  return $items;
}

/**
* Implements hook_element_info().
*/

function telisim_element_info() {
  return array(
    'telisim_notepad' =&gt; array(
      '#input' =&gt; TRUE,
      '#process' =&gt; array('porta_teslisim_notepad_process_callback'),
      '#theme_wrappers' =&gt; array('telisim_inline_form_element'),
    ),
  );
}

function porta_teslisim_notepad_process_callback($element, &amp;$form_state, $complete_form) {

 $element['#tree'] = TRUE;

  // Normal FAPI field definitions, except that #value is defined.
  $element['areacode'] = array(
    '#type' =&gt; 'textfield',
    '#size' =&gt; 3,
    '#maxlength' =&gt; 3,
    '#value' =&gt; $element['#value']['areacode'],
    '#required' =&gt; TRUE,
    '#prefix' =&gt; '(',
    '#suffix' =&gt; ')',
  );
  $element['prefix'] = array(
    '#type' =&gt; 'textfield',
    '#size' =&gt; 3,
    '#maxlength' =&gt; 3,
    '#required' =&gt; TRUE,
    '#value' =&gt; $element['#value']['prefix'],
  );
  $element['extension'] = array(
    '#type' =&gt; 'textfield',
    '#size' =&gt; 4,
    '#maxlength' =&gt; 4,
    '#value' =&gt; $element['#value']['extension'],
  );

   return $element;

  }

  function _telisim_element_theme() {
  return array(
    'telisim_inline_form_element' =&gt; array(
      'render element' =&gt; 'element',
      'file' =&gt; 'telisim.module',
    ),
    'telisim_checkbox' =&gt; array(
      'render element' =&gt; 'element',
      'file' =&gt; 'telisim.module',
    ),
  );
}


function telisim_examples($form, &amp;$form_state){

  $form['a_form_example_element_discrete'] = array(
    '#type' =&gt; 'telisim_notepad',
    '#title' =&gt; t('Discrete phone number'),
    '#default_value' =&gt; variable_get(
      'form_example_element_discrete',
      array(
        'areacode' =&gt; '999',
        'prefix' =&gt; '999',
        'extension' =&gt; '9999',
      )
    ),
    '#description' =&gt; t('A phone number : areacode (XXX), prefix (XXX) and extension (XXXX).'),
  );

   dsm($form);
    return $form;
}
I see two problems:

1) Your hook_theme() implementation is named incorrectly, meaning it will never be called. This:

_telisim_element_theme()


Should be this:

telisim_theme()


2) You haven't implemented theme_telisim_inline_form_element(), so there is no HTML for the form element to render.

You need to create this function, and output the relevant HTML for your form element inside the function.