Nostalrius Begins - Quality wow vanilla realm (1.12)

So ,when i finish one quest and get another quest right away, sometimes when i accept it it says " you do not meet requierments for that game". I dont get a quest, and i can never take it. The only way i could (maybe) get it is if someone shared it to me. Any idea how to prevent this?
Happened to me atleast 5 times until now, and its really getting annoying as im running out of quests.