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     149600   1. {main}() /var/www/chemiewerkt/index.php:0
    0.1495    5824368   2. SJB_Request->execute() /var/www/chemiewerkt/index.php:81
    0.1495    5824816   3. SJB_System::getPage() /var/www/chemiewerkt/system/core/Request.php:212
    0.1497    5837884   4. SJB_PageConstructor::getPage() /var/www/chemiewerkt/system/core/System.php:331
    0.1570    6181540   5. SJB_System::executeFunction() /var/www/chemiewerkt/system/core/PageConstructor.php:43
    0.1570    6181564   6. SJB_ModuleManager->executeFunction() /var/www/chemiewerkt/system/core/System.php:189
    0.1597    6268264   7. SJB_Classifieds_SearchResults->execute() /var/www/chemiewerkt/system/core/ModuleManager.php:141
    0.1652    6605240   8. SJB_SearchResultsTP->getChargedTemplateProcessor() /var/www/chemiewerkt/system/user-scripts/classifieds/search_results.php:169
    0.1679    6628376   9. SJB_SearchResultsTP->_getListingSidCollectionFromRequest() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:92
    0.1987    7893412  10. SJB_SearchFormBuilder::extractCriteriaFromRequestData() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:447
    0.2050    8223640  11. SJB_ObjectProperty->isComplex() /var/www/chemiewerkt/system/lib/classifieds/SearchEngine/SearchFormBuilder.php:124