Ошибки в error_log от Phoca Guestbook - Модули и плагины

При включении CAPTCHA гостевой книги пишет ошибки в логах. Подскажите, что это за ошибки, почему происходят и как устранить?!

[19-Apr-2015 11:48:03 Europe/Moscow] PHP Strict Standards:  Non-static method PhocaguestbookHelperCaptchaEasycalc::createCaptchaData() should not be called statically, assuming $this from incompatible context in /home/public_html/components/com_phocaguestbook/models/fields/phocacaptcha.php on line 52
[19-Apr-2015 11:48:03 Europe/Moscow] PHP Strict Standards:  Non-static method PhocaguestbookHelperCaptchaEasycalc::converttostring() should not be called statically, assuming $this from incompatible context in /home/public_html/components/com_phocaguestbook/helpers/phocaguestbookcaptcha.php on line 624
[19-Apr-2015 11:48:03 Europe/Moscow] PHP Strict Standards:  Non-static method PhocaguestbookHelperCaptchaEasycalc::converttostring() should not be called statically, assuming $this from incompatible context in /home/public_html/components/com_phocaguestbook/helpers/phocaguestbookcaptcha.php on line 630