Добрый день, при использовании phpthumbon выдаётся ошибка

Fatal error: Uncaught Error: Call to a member function make() on null in /home/1/1/core/components/phpthumbon/model/phpthumbon/phpthumbon.class.php:588 Stack trace: #0 /home/1/1/core/components/phpthumbon/model/phpthumbon/phpthumbon.class.php(324): phpThumbOn->makeDir('/home/1/...') #1 /home/1/1/core/components/phpthumbon/model/phpthumbon/phpthumbon.class.php(284): phpThumbOn->makeCacheDir() #2 /home/1/1/core/cache/includes/elements/modx/revolution/modsnippet/52.include.cache.php(24): phpThumbOn->run(Array) #3 /home/1/1/core/src/Revolution/modScript.php(88): include('/home/1/...') #4 /home/1/1/core/src/Revolution/modX.php(1923): MODX\Revolution\modScript->process(NULL) #5 /home/1/1/core/src/Revolution/Filters/modOutputFilter.php(754): MODX\Revolution\modX->runSnippet('phpthumbon', Array) #6 /home/1/1/core/src/Revolution/modTag.php(354): MODX\Revolution\Filters\modOutputFilter->filter(Object in /home/1/1/core/components/phpthumbon/model/phpthumbon/phpthumbon.class.php on line 588

картинку выводил вот так


подскажите пожалуйста, в чём может быть проблема