Release date

Hello, I can't change the start date of a series. This is a french series (https://www.imdb.com/fr/title/tt0173580/?ref_=ra_dc_ln) and "1990" is an incorrect date. The first episode of this series (L'Enfer au soleil) was broadcast on october 25, 1988 as you can see on TMDB (https://www.themoviedb.org/tv/221969-mesaventures/season/1/episode/1?language=fr) When I try to change the release dates, there is no option to add an item. Could someone help me? Thanks in advance.