I try to make an application that communicate server by udp. i easly send data from client(j2me device) to server. but there is problem when i try to send data from server to client.

i make server pc as both server and client, and phone become also both server and same time client.
when i send a data from phone to server, i use phone's client side and send data to server pc's server side. and when i send data from server to phone.

my code is working good in emulators. but, in real device, it dont work.
where is problem, do you think?