error on sites > navigation

[Broekhuis]

Hi,
I installed ItemSetsTree in Omeka S. When I press on "sites > navigation" of my site, I get the error below. Any idea what could be wrong?

Error
Class 'ItemSetsTree\Site\Navigation\Link\ItemSetsTree' not found

Details:

Error: Class 'ItemSetsTree\Site\Navigation\Link\ItemSetsTree' not found in /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-servicemanager/src/Factory/InvokableFactory.php:27
Stack trace:
#0 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-servicemanager/src/ServiceManager.php(615): Laminas\ServiceManager\Factory\InvokableFactory->__invoke(Object(Laminas\ServiceManager\ServiceManager), 'ItemSetsTree\Si...', NULL)
#1 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-servicemanager/src/ServiceManager.php(234): Laminas\ServiceManager\ServiceManager->doCreate('ItemSetsTree\Si...')
#2 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-servicemanager/src/AbstractPluginManager.php(171): Laminas\ServiceManager\ServiceManager->get('itemSetsTree')
#3 /home/deb16431n1/domains/mydomein.nl/public_html/application/src/Site/Navigation/Link/Manager.php(17): Laminas\ServiceManager\AbstractPluginManager->get('itemSetsTree', Array, true)
#4 /home/deb16431n1/domains/mydomein.nl/public_html/application/src/View/Helper/NavigationLink.php(39): Omeka\Site\Navigation\Link\Manager->get('itemSetsTree')
#5 /home/deb16431n1/domains/mydomein.nl/public_html/application/view/omeka/site-admin/index/navigation.phtml(39): Omeka\View\Helper\NavigationLink->getName('itemSetsTree')
#6 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-view/src/Renderer/PhpRenderer.php(519): include('/home/deb16586n...')
#7 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-view/src/View.php(194): Laminas\View\Renderer\PhpRenderer->render(NULL)
#8 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-view/src/View.php(222): Laminas\View\View->render(Object(Laminas\View\Model\ViewModel))
#9 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-view/src/View.php(187): Laminas\View\View->renderChildren(Object(Laminas\View\Model\ViewModel))
#10 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-mvc/src/View/Http/DefaultRenderingStrategy.php(98): Laminas\View\View->render(Object(Laminas\View\Model\ViewModel))
#11 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-eventmanager/src/EventManager.php(319): Laminas\Mvc\View\Http\DefaultRenderingStrategy->render(Object(Laminas\Mvc\MvcEvent))
#12 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-eventmanager/src/EventManager.php(171): Laminas\EventManager\EventManager->triggerListeners(Object(Laminas\Mvc\MvcEvent))
#13 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-mvc/src/Application.php(360): Laminas\EventManager\EventManager->triggerEvent(Object(Laminas\Mvc\MvcEvent))
#14 /home/deb16431n1/domains/mydomein.nl/public_html/vendor/laminas/laminas-mvc/src/Application.php(341): Laminas\Mvc\Application->completeRequest(Object(Laminas\Mvc\MvcEvent))
#15 /home/deb16431n1/domains/mydomein.nl/public_html/index.php(21): Laminas\Mvc\Application->run()
#16 {main}

[Broekhuis]

Nevermind, I just discovered that not all files and folders had been transferred... Problem is solved :) Thanks.