No valid devices were found on which we can create a new filesystem

Hi Admins.

I have an a case that I'm confused. I have a Dell server where I installed RHEL6.5 and configured. But later on customer requested to install RHEL5.5. I inserted new iso image to the server and when I boot via DVD is show installation process but when it come to choose the hard drive I'm not seeing any drives. It's erroring with "No valid devices were found on which we can create a new filesystem". As a troubleshoot I recreated raid configuration on the server, but still same issue. What might be the issue? Driver? or ????