This is the hook code that renders the subscription form:
```
if (!$this->customerqty ||
!Configuration::get('PSSTOCKMANAGEMENT') ||
Product::isAvailableWhenOutOfStock($params['product']->outof_stock)
) {
return '';
}
$context = Context::getContext();
$idProduct = (int) $params['product']->id;
$idProductAttribute = 0;
$idCustomer = (int) $context->customer->id;
if ((int) $context->customer->id <= 0) {
$this->context->smarty->assign('email', 1);
} elseif (MailAlert::customerHasNotification($idCustomer, $idProduct, $idProductAttribute, (int) $context->shop->id)) {
return '';
}
```
If nothing is rendered, then the only explanations are:
1) hooks is actually not triggered -- please ensure that the module is enabled
2) Product Availability option is disabled in mailalerts module configuration
3) Enable stock management is disabled in Preferences > Products
4) product can be ordered even when out of stock (although this should be bypassed by your modification)
5) user is logged in, and has already submitted mail alert