Magento - Programmatically added products don't show up

I am trying to import products using a custom made import profile. Here I set some values on the product and then save it, like this:

$product = Mage::getModel('catalog/product');
$data = array();
// Inbetween I fill $data with some values
$product->addData($data);
$product->save();

However, the products do show up in the admin, but do not show up on the frontend (I did add them to catego开发者_运维问答ries).

The odd thing is, they do appear on the frontend once I open them in the admin and save them again (without modifying anything). Am I forgetting something, or some value that is somehow set by that action?

I tried to rebuild all indices in the backend and to clear the cache, but this does not work, contrary to Magento API: Rebuild Indexes after adding new products.

I had the same problem and solved it by adding the Website ID to the product:

$newProduct ->setWebsiteIds(array(1))

Keep in mind that the parameter is an array, so you can add multiple website td's

Some guesses, since this comes up from time to time. See also here.