" Error when trying to add new domain. "That is not a valid Subdomain/FTP username"

[boondoggle]

I get the message "That is not a valid Subdomain/FTP username" when I try to add a new add on domain. I had no problems registering the domain so there shouldnt be a problem with the name. The "new domain name" field has a tick next to it but the subdomain/FTP username populates automatically and comes up with the error message.
Surely if the domain name is valid then it should be a valid subdomain/FTP username?
Its a .co.uk domain and 29 digits long including 3 hyphens (ie 4 words)
Ive registered similar domains before so I don't know what the problem is.

Any experts care to help.
Many thanks in advance

[VodaHost]

Re: " Error when trying to add new domain. "That is not a valid Subdomain/FTP usernam

Please submit a support ticket and our staff will add the addon domain for you...click below...

https://www.vodasupport.com