id form error?

in function

function simplenews_multisignup_form_alter(&$form, $form_state, $form_id) {
-    if ($form_id == 'simplenews-subscription-manager-form') {
+  if ($form_id == 'simplenews_subscription_manager_form') {
    if (!empty($form['#parameters'][2]) && $form['#parameters'][2] == 'simplenews_multisignup') {
      // Get rid of the fieldset to save screen space.
      unset($form['subscriptions']['#type']);
      // Prevent the form from redirecting to the front page.
      $form['#redirect'] = FALSE;
    }
  }
}

the form ids in hook_form_alter change caracter '-' to '_'