Forumlar / Cotonti / Extensions / Tag searching with comma (logical AND) ?

Is there a problem with tag cloud plugin tag search with logical AND, or am i trying it wrongly?

It is written that comma(,) will be considered as logical AND and semicolon(;) will be logical OR.

Semicolon works well but I havent received any result from each search with comma.
How must it be done to get results?

Thanks.