This is definitely being called

function studiga_theme_theme($existing, $type, $theme, $path) {    
    $items['add_property_form'] = array(
        'render element' => 'form',
        'template' => 'node--14',
        'path' => drupal_get_path('theme', 'studiga_theme') . '/templates/node',
    );

    return $items;
}

But which should set up the form fields isn't and I have no idea why

function studiga_theme_preprocess_add_property_form(&$variables) { 
 
  // Shorten the form variable name for easier access.
  $form = $variables['form'];
 
  $form['first_name'] = array(
        '#type' => 'textfield',
        '#attributes' => array('placeholder' => t('First name')),
    );
    $form['last_name'] = array(
        '#type' => 'textfield',
        '#attributes' => array('placeholder' => t('Last name')),
    );
    $form['address'] = array(
        '#type' => 'textfield',
        '#attributes' => array('placeholder' => t('Address')),
    );
    $form['city'] = array(
        '#type' => 'textfield',
        '#attributes' => array('placeholder' => t('City')),
    );
    $form['state'] = array(
        '#type' => 'select',
        '#options' => array(
            'default' => 'State',
            '...' => '...',
        ),
    );
    $form['zip'] = array(
        '#type' => 'textfield',
        '#attributes' => array('placeholder' => t('Zip')),
    );
    $form['email'] = array(
        '#type' => 'textfield',
        '#attributes' => array('placeholder' => t('Email')),
    );
    $form['phone'] = array(
        '#type' => 'textfield',
        '#attributes' => array('placeholder' => t('Phone')),
    );
    $form['submit'] = array(
        '#type' => 'submit',
        '#value' => 'Submit',
    );   
}

Thanks