Object of class stdClass could not be converted to string

Hi

I tried chatroom, latest 2.16,
but I didn't see any chat, nothing, on the chat page. No message, nothing about if chat is loading.
I found this in my watchdog, it is the error from chatroom page

Object of class stdClass could not be converted to string in /home/users/somvprahe.sk/web/www/sites/all/modules/rules/rules/modules/php.rules.inc(89) : eval()'d code on line 12.

I tried uninstall module and enabled again, it doesn't help.