Technical issues with Heroes III.

I'm writing in more detail: I downloaded "Heroes Platinum" from the internet, installed it, but when I play, it asks for the disc. I found the "Breath of Death" disc, and everything works, but when I start a game over the network, either I can't find the other player, or they can't find me, or we enter the game and after about five minutes, one of us gets kicked out, and it says that the player has left the network, and that I've become the server, and the same message appears for the other player. Could it be because my "Breath of Death" disc is version 3.2, while "Platinum" is version 4.0? I don't understand anything... Help!