Fatal error: Call to a member function isComplex() on a non-object in /var/www/chemiewerkt/system/lib/orm/ObjectProperty.php on line 174

Call Stack:
    0.0004     150208   1. {main}() /var/www/chemiewerkt/index.php:0
    1.6348    5822332   2. SJB_Request->execute() /var/www/chemiewerkt/index.php:81
    1.6349    5822780   3. SJB_System::getPage() /var/www/chemiewerkt/system/core/Request.php:212
    1.6351    5835848   4. SJB_PageConstructor::getPage() /var/www/chemiewerkt/system/core/System.php:331
    1.6667    6179496   5. SJB_System::executeFunction() /var/www/chemiewerkt/system/core/PageConstructor.php:43
    1.6667    6179520   6. SJB_ModuleManager->executeFunction() /var/www/chemiewerkt/system/core/System.php:189
    1.7017    6266232   7. SJB_Classifieds_SearchResults->execute() /var/www/chemiewerkt/system/core/ModuleManager.php:141
    1.7471    6603256   8. SJB_SearchResultsTP->getChargedTemplateProcessor() /var/www/chemiewerkt/system/user-scripts/classifieds/search_results.php:169
    1.7497    6626224   9. SJB_SearchResultsTP->_getListingSidCollectionFromRequest() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:92
    2.1613    7949720  10. SJB_SearchFormBuilder::extractCriteriaFromRequestData() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:447
    2.1884    8279920  11. SJB_ObjectProperty->isComplex() /var/www/chemiewerkt/system/lib/classifieds/SearchEngine/SearchFormBuilder.php:124