I have been waiting to watch a German movie called ‘kissing my sister ‘ and was unsuccessful, it was on my watch list

That film was released in the year 2000. Unless it is rerun on TV, you're unlikely to get a notification that is available to view (and that assumes you've set your email preferences to receive such emails).

But, by using Google, and clicking the Videos category, looks like it might be on YouTube:
https://www.google.com/search?q=Der+Ku%C3%9F+meiner+Schwester&rlz=1C1CHBF_enUS834US834&source=lnms&tbm=vid&sa=X&ved=0ahUKEwjj5_HcvaPkAhVHR60KHQzlCTAQ_AUIESgB&biw=1364&bih=665

Here's more information about Watchlist, in case it helps.
https://help.imdb.com/article/imdb/track-movies-tv/watchlist-faq/G9PA556494DM8YBA?ref_=helpsrall#