How to handle error: service xvfb does not support chkconfig?

When I followed the installation instructions below to install xvfb, I get the following error:

service xvfb does not support chkconfig

Installation Instructions

   Install Xvfb (via the RHEL Server Optional repository)
    # yum -y install xorg-x11-server-Xvfb
    # yum -y install mesa-dri-drivers
    # yum -y install dbus-x11
    # dbus-uuidgen --ensure
    Setup Xvfb as a service
    # useradd xvfb
    # vim /etc/init.d/xvfb
    # chkconfig --add xvfb
    # chkconfig xvfb on