Invalid Block Type Joomlart_Jmslideshow_Block_List

I’ve tried to install the JM Product Slider from the Ores Theme using the installation guide. When I add the Product Slider Block to the content of the home page, I get an Invalid Block Type Exception. How can I fix this?
Block Code:
{{block type=”joomlart_jmproductsslider/list” name=”jmproductsslider”}}
Stack Trace:
exception ‘Mage_Core_Exception’ with message ‘Invalid Block Type: Mage_Joomlart_Jmslideshow_Block_List’ in /var/www/virtual/b3rgmann/magento.b3rgmann.mensa.uberspace.de/app/Mage.php:595
Stack trace:
#0  /var/www/virtual/…/app/code/core/Mage/Core/Model/Layout.php(495): Mage::throwException(‘Ung??ltiger Blo…’)
#1  /var/www/virtual/…/app/code/core/Mage/Core/Model/Layout.php(437): Mage_Core_Model_Layout->_getBlockInstance(‘joomlart_jmslid…’, Array)
#2  /var/www/virtual/…/app/code/core/Mage/Core/Model/Layout.php(472): Mage_Core_Model_Layout->createBlock(‘joomlart_jmslid…’, ‘jmslideshow’)
#3  /var/www/virtual/…/app/code/core/Mage/Core/Model/Layout.php(239): Mage_Core_Model_Layout->addBlock(‘joomlart_jmslid…’, ‘jmslideshow’)
#4  /var/www/virtual/…/app/code/core/Mage/Core/Model/Layout.php(205): Mage_Core_Model_Layout->_generateBlock(Object(Mage_Core_Model_Layout_Element), Object(Mage_Core_Model_Layout_Element))
#5  /var/www/virtual/…/app/code/core/Mage/Core/Model/Layout.php(210): Mage_Core_Model_Layout->generateBlocks(Object(Mage_Core_Model_Layout_Element))
#6  /var/www/virtual/…/app/code/core/Mage/Core/Controller/Varien/Action.php(344): Mage_Core_Model_Layout->generateBlocks()
#7  /var/www/virtual/…/app/code/core/Mage/Core/Controller/Varien/Action.php(269): Mage_Core_Controller_Varien_Action->generateLayoutBlocks()
#8  /var/www/virtual/…/app/code/core/Mage/Checkout/controllers/CartController.php(177): Mage_Core_Controller_Varien_Action->loadLayout()
#9  /var/www/virtual/…/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Checkout_CartController->indexAction()
#10 /var/www/virtual/…/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(250): Mage_Core_Controller_Varien_Action->dispatch(‘index’)
#11 /var/www/virtual/…/app/code/core/Mage/Core/Controller/Varien/Front.php(172): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#12 /var/www/virtual/…/app/code/core/Mage/Core/Model/App.php(354): Mage_Core_Controller_Varien_Front->dispatch()
#13 /var/www/virtual/…/app/Mage.php(684): Mage_Core_Model_App->run(Array)
#14 /var/www/virtual/…/index.php(87): Mage::run(”, ‘store’)
#15 {main}