Software :: Run GUI Application From Userdefined Boot Time Daemon Server

I am writing one simple server daemon and running with /etc/init.d/server its running properly but when i want to run one simple QT GUI with system() function , its not able to run it and returning 256 as return code .

if same daemon i m running from terminal then its working properly and also system() function is getting success with return value 0 and GUI is getting popped up.

i m using ubuntu-9.10 below is the code ....

#include <stdio.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>

[Code].....