During install error centos 5.8

Hi
i am getting the following error while i try to install OS from my repo
" unable to read group information from repositories this is a problem with the generation of your install tree "

guide me any one

Guide us by providing more information. What you have provided so far is insufficient to determine root cause of your problem.

i have a kickstart file, When i try to install from ks file i am getting the follwing error during the install.
I have uploaded my ks file
From my repo server
yum list is working fine,
yum grouplist is not showing any thing getting following error

[root@eplnx021 html]# yum grouplist
Loaded plugins: downloadonly, fastestmirror, security
Setting up Group Process
Loading mirror speeds from cached hostfile
Error: No group data available for configured repositories
[root@eplnx021 html]#

question is how to configure the group list in yum if this works fine my install also will be fine