Test enviroment always forwards to main url

[THX_Ultra]

Hi maybe one of you can help, since I just don't find the error or the mistake that I made.

We ar running this board www.r-l-x.de and I wanted to clone it to have a new testing environment
since the old test board kind of crashed

So I set it up on r-l-x.biz - I changed the database entries for the forum url from r-l-x.de to r-l-x.biz - but as soon as I enter the url - it immediately redirects me to the r-l-x.de site.

Honestly I don't what is wrong, maybe one of you can give me a hint.

Thanks so much, Michael