You are WHMCS owner and you got this error message? IP Registration (Registrar Error Invalid Client IP)

I have Enom registar active in my WHMCS (Setup/Products/Domain Registars) and i got above error.

Issue is that you need to manually open ticket with enom:
http://www.enom.com/help/

In this ticket state your enom username (found in WHMCS / Setup / Products, Services / Domain registars) and IP address to unblock (in WHMCS you should be able to see so called "To Do" entries and if domain registration failed, you can see new To Do entry and IP address which failed. Also you may receive WHMCS report email with the IP address. Also include in your Enom support request IP of your webhosting site.

Hope it will help you