Had already done the usual VNC configuration such as uncommenting
# Uncomment the following two lines for normal desktop: unset SESSION_MANAGER exec /etc/X11/xinit/xinitrcin .vnc/xstartup but still no luck.
After some searching one suggestion was to install X windows system.
yum groupinstall "X Window System"Run VNC again blank screen has disappeared but the desktop is still not "nice".
Installed gnome desktop
yum groupinstall "GNOME Desktop Environment"and change the twm with gnome in .vnc/xstartup
#gnome-session & twm &No difference still the same desktop as before. Finally decided to installed KDE desktop
yum groupinstall "kde-desktop"Finally the "nice" desktop.
It's not necessary to install X-windows and gnome desktop and then KDE. Installing KDE desktop when the blank screen is visible will resolve the blank screen issue.