[CentOS] can not install CentOS as VM in KVM

Hi to all,

I am trying to install CentOS 5.5 as VM on a KVM server running Ubuntu 10.04. The Problem: the installer does not find the iso image. (Direct copy from website downlod.) I can start CentOS from the iso and can even do some disk checks. But when I go further the installer says "no CDROm found". Pretty weird. I tried all CentOS 5.5. image available (Live CD, net install, bin 1 of 8, 32 bit and 64 bit). Other installation (Debin, Ubuntu, SLES, Windows XP, Windows 7, Windows Server 2008) worked fine.

Perhaps somebody can help me in setting things up for that.

Michael