Fatal error: Call to a member function setObjectSID() on a non-object in /var/www/chemiewerkt/system/lib/orm/ObjectProperty.php on line 137

Call Stack:
    0.0004     148840   1. {main}() /var/www/chemiewerkt/index.php:0
    0.2965    6048792   2. SJB_Request->execute() /var/www/chemiewerkt/index.php:81
    0.2991    6050528   3. SJB_System::getPage() /var/www/chemiewerkt/system/core/Request.php:228
    0.2994    6063596   4. SJB_PageConstructor::getPage() /var/www/chemiewerkt/system/core/System.php:331
    0.3080    6407228   5. SJB_System::executeFunction() /var/www/chemiewerkt/system/core/PageConstructor.php:43
    0.3080    6407252   6. SJB_ModuleManager->executeFunction() /var/www/chemiewerkt/system/core/System.php:189
    0.3101    6520460   7. SJB_Classifieds_DisplayListing->execute() /var/www/chemiewerkt/system/core/ModuleManager.php:141
    0.3122    6629620   8. SJB_ListingManager::getObjectBySID() /var/www/chemiewerkt/system/user-scripts/classifieds/display_listing.php:82
    0.3880    7855080   9. SJB_Object->setSID() /var/www/chemiewerkt/system/lib/classifieds/Listing/ListingManager.php:56
    0.3880    7855112  10. SJB_ObjectDetails->setObjectSID() /var/www/chemiewerkt/system/lib/orm/Object.php:34
    0.3880    7855308  11. SJB_ObjectProperty->setObjectSID() /var/www/chemiewerkt/system/lib/orm/ObjectDetails.php:41