Network Maxconnection problem

I got a problem in declaring how many connections can be connected to one server. Basically, i want to make games for 4 players max. But, the result is there are only 3 players who can play (1 server, 2 client).

Here is the code for initializing the server :

Network.InitializeSecurity();
Network.InitializeServer(4, listenPort, false);
Network.maxConnections = 0;

Is there anything wrong with this code? anyone please help, i would be very appreciate that. Thanks :)