Mageworx Customer Credit Extension failing under Magento 1.5.1.0 http://[…]/index.php/admin/system_config/edit/section/mageworx_customers/key/[…]
Warning: include(Mage/Adminhtml/Model/System/Config/Source/Customer/Group/Multiselect.php): failed to open stream: No such file or directory in /home/www/ybus/magento/lib/Varien/Autoload.php on line 93
#0 /home/www/ybus/magento/lib/Varien/Autoload.php(93): mageCoreErrorHandler(2, 'include(Mage/Ad...', '/home/m/www/ybu...', 93, Array)
#1 /home/www/ybus/magento/lib/Varien/Autoload.php(93): Varien_Autoload::autoload()
#2 [internal function]: Varien_Autoload->autoload('Mage_Adminhtml_...')
#3 [internal function]: spl_autoload_call('Mage_Adminhtml_...')
#4 /home/www/ybus/magento/app/code/core/Mage/Core/Model/Config.php(1252): class_exists('Mage_Adminhtml_...')
#5 /home/www/ybus/magento/app/Mage.php(432): Mage_Core_Model_Config->getModelInstance('adminhtml/syste...', Array)
#6 /home/www/ybus/magento/app/Mage.php(446): Mage::getModel('adminhtml/syste...', Array)
#7 /home/www/ybus/magento/app/code/core/Mage/Adminhtml/Block/System/Config/Form.php(385): Mage::getSingleton('adminhtml/syste...')
#8 /home/www/ybus/magento/app/code/core/Mage/Adminhtml/Block/System/Config/Form.php(204): Mage_Adminhtml_Block_System_Config_Form->initFields(Object(Varien_Data_Form_Element_Fieldset), Object(Mage_Core_Model_Config_Element), Object(Mage_Core_Model_Config_Element))
#9 /home/www/ybus/magento/app/code/core/Mage/Adminhtml/Block/System/Config/Edit.php(92): Mage_Adminhtml_Block_System_Config_Form->initForm()
#10 /home/www/ybus/magento/app/code/core/Mage/Adminhtml/controllers/System/ConfigController.php(101): Mage_Adminhtml_Block_System_Config_Edit->initForm()
#11 /home/www/ybus/magento/app/code/core/Mage/Core/Controller/Varien/Action.php(420): Mage_Adminhtml_System_ConfigController->editAction()
#12 /home/www/ybus/magento/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(253): Mage_Core_Controller_Varien_Action->dispatch('edit')
#13 /home/www/ybus/magento/app/code/core/Mage/Core/Controller/Varien/Front.php(176): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#14 /home/www/ybus/magento/app/code/core/Mage/Core/Model/App.php(340): Mage_Core_Controller_Varien_Front->dispatch()
#15 /home/www/ybus/magento/app/Mage.php(627): Mage_Core_Model_App->run(Array)
#16 /home/www/ybus/index.php(85): Mage::run('ybus')
#17 {main}
app/code/local/MageWorx/CustomerCredit/etc/system.xml:227
<source_model>adminhtml/system_config_source_customer_group_multiselect</source_model>
