Did you make sure when you installed where it stated on install to set your wowbb cookie name?
If it is set check your other cookie settings as surely not set
cookie prefix should be empty
cookie domain should be .base4art.co.uk
cookie path should be /
If you correct this situation login should be recognized. If the cookies are set right then the only other thing it can be is as we have previously discussed an old wowbb.php file