TOPIC: Installation Problem....please help

I use Joomla 1.015

I just tried to install joomlacomment 3.26 after first uninstall the 3.12b ver.

I got error about in the component\com_comment folde already installed component..
so I manually delete the commponent/com_comment folder

then I install....n then
hey... what's the meaning of this error msg??

Fatal error: Undefined class name 'jostableutils' in /home/sloki/user/t65681/sites/arievianza.com/www/administrator/components/com_comment/install.comment.php on line 40

please help...anyone!

What should I do??