I am trying to access SOAP through the API User, but I am always gettings the error below. The Username and Password is correct. I think it might have something to do with the DB Tables api_role and api_user. I have tried it with the administrator role and also a custom role, both fail. I have no idea how to fix it 
<pre>Parent Role id 'G8' does not exist
#0 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/lib/Zend/Acl.php(143): Zend_Acl_Role_Registry->add(Object(Mage_Api_Model_Acl_Role_User), 'G8')
#1 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Api/Model/Mysql4/Acl.php(99): Zend_Acl->addRole(Object(Mage_Api_Model_Acl_Role_User), 'G8')
#2 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Api/Model/Mysql4/Acl.php(65): Mage_Api_Model_Mysql4_Acl->loadRoles(Object(Mage_Api_Model_Acl), Array)
#3 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Api/Model/Session.php(101): Mage_Api_Model_Mysql4_Acl->loadAcl()
#4 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Api/Model/Server/Handler.php(39): Mage_Api_Model_Session->login('xxxxxxxx', 'xxxxxxxx')
#5 [internal function]: Mage_Api_Model_Server_Handler->login('xxxxxxxx', 'xxxxxxxx')
#6 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Api/Model/Server/Adapter/Soap.php(132): SoapServer->handle()
#7 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Api/Model/Server.php(76): Mage_Api_Model_Server_Adapter_Soap->run()
#8 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Api/controllers/SoapController.php(42): Mage_Api_Model_Server->run()
#9 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Core/Controller/Varien/Action.php(418): Mage_Api_SoapController->indexAction()
#10 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Core/Controller/Varien/Router/Standard.php(258): Mage_Core_Controller_Varien_Action->dispatch('index')
#11 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Core/Controller/Varien/Front.php(177): Mage_Core_Controller_Varien_Router_Standard->match(Object(Mage_Core_Controller_Request_Http))
#12 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/code/core/Mage/Core/Model/App.php(304): Mage_Core_Controller_Varien_Front->dispatch()
#13 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/app/Mage.php(596): Mage_Core_Model_App->run(Array)
#14 /var/www/vhosts/old.xxxxxxxx.de/httpdocs/index.php(80): Mage::run('', 'store')
#15 {main}</pre>
