Jcompress : Class 'JFolder' not found...

Hi, I have installed your plugin for test on my test website CGPME Nouvelle-Calédonie | Notre valeur ajoutée, c'est l'homme - This is a 3.3.6 Joomla, and every things worked very well. I was really excited to have found your plugin and have let a comment in your blog to thank you.
Now I have tried to use it on another website wich need some opitimisation : Accueil - Le Ponton . It is also a 3.3.6 Jomla website, one page (for the moment) with a Yootheme template too and it is on the ame server (SiteGround). But on this one, when i try to edit the plugin on backend, i get this message :
Is there anything i can do to make it work there ? I have an admintool installed on this one, maybe it come from here ?
I thank you by advance for any suggestion...

Are you sure your are posting in product assigned forum?: Yes

What is your CMS version?: Joomla 3.x

MySQL Version: 5.x

PHP version: 5.x

Link to installation: Accueil - Le Ponton

Have you edited any files? If yes tell us which ones.: No

Is this personal or client website?: Client

Sorry we missed this post , you posted in general forum instead of this one. I moved it now.

OK thnx much for testing , il look in to the bug
looks like jfile folder lib is missing ,
https://github.com/youjoomla/jcompre...gclear.php#L57

will fix that today and push new files on git.

ok bud , new one is up with few more options

move js files to bottom of the page ( gives another 4% up on GMetrix )
css fonts and images to data uri converter
code optimization
and fix for your bugs