Why can i sign in under yazak but not yahoo to yahoo chat rooms?

since the change of format to entering yahoo, i cannot enter yahoo rooms under yahoo nic but can under yazak. i enter aroom under yahoo follow the instruction and and am accepted and told to carry on chatting..but i still find just my nic and messenger in the box...yet on yazk it works. and no the rooms are not full. am i doing something wrong...hope to hear from someone...thanks