I have played over 200 games on Tygem seldom with any problem during the counting (well, sometimes I’m unhappy that I lost

. Recently, at the end of games, after I have passed, I have started getting a message to designate the dead stones. Well, on the Japanese Panda board, this is the norm. Panda shows which stones are in question and you and your opponent mark the dead ones. With Tygem I don’t get a screen to mark the dead stone, nor can I use the game screen to mark the dead stones. I don’t see any evidence that my opponent has marked my dead stones.
In my most recent game the score was close (I was ahead 4.5 with a Chinese 7D player). I was repeatedly asked to designate dead stones; on Tygem I don’t know how to designate them. Between requests to designate, Tygem would ask me if I agreed with the scoring, which I would agree. Apparently, my opponent wouldn’t. After several cycles of these requests to designate dead stones & agree to the score, my opponent agreed.
How is one supposed to designate the dead stones?