Blank Screen on a RHEL 6.4 using Xephyr.

Here's is my configuration.

Edited /etc/gdm/custom.conf for the following:

[xdmcp]
Enable=true

[security]
DisAllowTCP=false

Also edited /etc/ssh/sshd_config and uncommented the following:

X11Forwarding yes
X11DisplayOffSet 10
X11UseLocalHost yes

Then edited /etc/pam.d/xserver

edit /etc/pam.d/xserver, and remove this line:
auth sufficient /lib/security/pam_rootok.so
now change the line that says:
auth required /lib/security/pam_console.so
to read:
auth required /lib/security/pam_permit.so

I rebooted the system and tested X. It worked but not Xypher
X :1 -query