problem with recvfrom

I have a problem with recvfrom(). I get a message and no error occurs,
but the struct sockaddr* from is not filled with sender's data.

The client's source code:

#include "reversi.h"
-------------------------------------------------------------------
int main() {
int socket_id = socket(PF_INET,SOCK_DGRAM,0);
struct sockaddr_in adres;
adres.sin_family = PF_INET;
adres.sin_port = htons(PORT_NR);
adres.sin_addr.s_addr = inet_addr("127.0.0.1");
cli_msg msg;
msg.type = CMT_LOGIN;
sendto(socket_id,&msg,sizeof(cli_msg),0,(struct sockaddr*)&adres,sizeof
(struct sockaddr));
printf("wyslalem na 127.0.0.1\n");
ser_main_msg ser_msg;
unsigned int rozmiar;
recvfrom(socket_id,&ser_msg,sizeof(ser_main_msg),0 ,(struct sockaddr*)
&adres,&rozmiar);
printf("otrzymalem cos a adresu %s",inet_ntoa(adres.sin_addr));
printf("type = %d\n",ser_msg.type);
return 1;
}
-------------------------------------------------------------------
All needed header files are included in reversi.h

Server is rather long, but the inportant part is, the socket is datagram
socket:
-------------------------------------------------------------------
bzero(&klient1, sizeof(struct sockaddr_in));
int ret = recvfrom(sockid,&msg_kli1,sizeof(cli_msg),0,(struc t sockaddr*)
&klient1,&rozmiar1);
printf("received %s, %d, %d\n",inet_ntoa(klient1.sin_addr), ret,
errno);
if (msg_kli1.type == CMT_LOGIN) {
msg.type = SMMT_WAIT;
sendto(sockid,&msg,sizeof(ser_main_msg),0,(struct sockaddr*)
&klient1,rozmiar1);
printf("send SMMT_WAIT to address %s\n",inet_ntoa
(klient1.sin_addr));
kli_nr++;
-------------------------------------------------------------------
serwer should print:
received 127.0.0.1, 16, 0
send SMMT_WAIT to addrress 127.0.0.1

but it prints:
reveived 0.0.0.0., 16, 0
send SMMT_WAIT to address 0.0.0.0

It happens only when I run the program on my computer, when I tried on
friends computer problem doesn't occur. Any ideas?

Omega