Your new IP must be your servers Base IP, which is the one CWP reads.
Additional IP's are only shown as that, additional IP's to be assigned to websites.
Just do a simple ifconfig from the CLI, and it will show your servers configured base IP as e.g. eth0 or eth0:0
Then your addon should shows as eth0:1, etc.
(NOTE: eth is only an example, it could start with almost anything)