xclock not runnnig for another user

I have install new solaris 10 in Virtual box in my pc. I have set below command as a root user. bash-3.2#export DISPLAY=":0.0" DISPLAY bash-3.2#xclock It is working fine for root user but I have another user named: mamun I have run xclock for "mamun" but it shows below error message. $xclock Xlib: connection to ":0.0" refused by server Xlib: No protocol specified Error: Can't open display: :0.0 How can I solve this problem?