Ok, this is not a regular post or page, this comes from BuddyPress template file. It sees they don’t use the regular <?php comments_template() ?> function in activity template file. The only way to turn on wpDiscuz on buddyPress activity page is editing activity template file and changing its comment function to WordPress Theme standard <?php comments_template() ?> function.
In the group of budypress we can write messages, but we do not any text editor. I know that all function are working, but when I the person who did know any bbcodes or something else, this is the reason why I need one text editor.