If you get this error message, it means your Cname is not well configured;)
I advise you to start from the beginning. There are three information to enter
1- Time to live:
It represents the time your members will keep the page on cache. Choose a long period of time (around 15 days is enough)
2- Name:
It is the particle before the domain name. For example:
name.your_domain.uk
If you want to have your forum on www.your_domain.uk, in that case the name =www If you want to have your forum on forum.your_domain.uk, in that case the name = forum.... etc
Started config. from beginning for the 100th time, and now it works ... Still don't know why i had a problem, because i used same settings before. Doesn't matter, it works now