Gnome Show Blank Screen

[Mohammad BadieZadegan]

Hi,
I Installed the last release of DragonflyBSD and then install Xorg without
any errors.
Now I Installed Gnome and while I try startx it's show me a blank screen.
BTW, I installed Xfce and now like Gnome I see blank screen when I try
startx!
Also I tested them with normal user and the root user.
How can I install at least one Desktop Environments?