Hi, I thing I've get rid of my problem above..
It seems that mibew has some database issue, if I'm not wrong, but please correct me if I'm saying something wrong
Last time before I got this kind of error, I'm kind of messed up a bit with the database and removing all chat data that I used for testing.. And here lies the problem, when I truncated table chat revision, then the chat system (visitors list) won't work normally again. So be sure that you don't mess up with table chat revision..
The easiest way and quickest way to get rid of this problem is by re-installed your mibew plugin again, but of course all changes that you've made will be removed as well.
The second way, you just need to open up your database and search for table 'chat revision'. And then you should Add 1 data for this table, with ID : some_number
Well, it works well for me after I do the second way.. Cause, if it will be so much trouble if you just re-install your mibew again and you have to customize its code again