Having trouble configuring Kloxo... IP Address issue

I'm relatively new to the Linux world, but I do have some knowledge, however I'm pretty much completely new to administering a linux box with a web control panel. From what I've seen so far Kloxo is the best free one that is most suited to me, so I'm trying to have a bit of a play around with it.

I get it all installed fine, and jump in to try and get things set up. I've found some step-by-steps on the net and the first basic thing they ask you to do (after the obvious "change administrator password" tasks, etc.) is to add a DNS Template. When I go to do that, I quickly get presented with an error saying "Alert: noipaddress". Ok, so I need to enter my Linodes public IP address in here. So I navigate to Servers > localhost > Ipaddresses. From here, I try and add a new IP address. The "Device Name" list is blank, and I put my Linodes IP address in and press Update. I straight away get presented with an error "Alert: someotherhostusesthis_ip". This is the bit that confuses me. From looking at other guides, I should even need to enter an IP Address, it should pick it up automatically. Am I missing something in my servers configuration? I also tried clicking "Re Read Ipaddress", which doesn't help.

EDIT: Just to clarify, I'm currently running CentOS 5.5. Most if not all documents I find are relating to 5.2, and a lot of the stuff is different in 5.5 by the looks of things. Bit of a shame that I can't install a CentOS 5.2 Linode :\