You've hidden PokerStars from the site list but that wouldn't prevent the HUD from working. If you want to put PokerStars back in that list go to 'Configure -> Sites & Import Options -> Site Configuration -> PokerStars' and disable the option to 'Hide Site From Lists'.
The most common cause of not having a HUD when playing on PokerStars tournaments is not running the PokerStars client in English:
PokerStars Configuration GuidePokerTracker 4 only supports English and the PokerStars client needs to be running in English (PokerStars Client -> Settings -> Global -> Language -> English) otherwise the HUD may not be able to attach correctly to the tables.