I have correctly noted the winning combination and claimed about BINGO, but the round ended and i didn’t win. Why?

If you receive the correctly daubed numbers and received the message, that someone claimed the Bingo faster than you, it means you claimed about Bingo later  than  the winners. Perhaps our server received the signal from you later than from the others or didn’t receive it at all. 

Bingo Kingdom is an online game, so you play with other people in real-time and the game’s result depends on the stability of your internet connection.