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:
    0.0005     150308   1. {main}() /var/www/chemiewerkt/index.php:0
    0.1767    5824528   2. SJB_Request->execute() /var/www/chemiewerkt/index.php:81
    0.1767    5824976   3. SJB_System::getPage() /var/www/chemiewerkt/system/core/Request.php:212
    0.1769    5838044   4. SJB_PageConstructor::getPage() /var/www/chemiewerkt/system/core/System.php:331
    0.1837    6181712   5. SJB_System::executeFunction() /var/www/chemiewerkt/system/core/PageConstructor.php:43
    0.1837    6181736   6. SJB_ModuleManager->executeFunction() /var/www/chemiewerkt/system/core/System.php:189
    0.1861    6268472   7. SJB_Classifieds_SearchResults->execute() /var/www/chemiewerkt/system/core/ModuleManager.php:141
    0.1909    6605516   8. SJB_SearchResultsTP->getChargedTemplateProcessor() /var/www/chemiewerkt/system/user-scripts/classifieds/search_results.php:169
    0.1934    6628480   9. SJB_SearchResultsTP->_getListingSidCollectionFromRequest() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:92
    0.2262    7940164  10. SJB_SearchFormBuilder::extractCriteriaFromRequestData() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:447
    0.2315    8270360  11. SJB_ObjectProperty->isComplex() /var/www/chemiewerkt/system/lib/classifieds/SearchEngine/SearchFormBuilder.php:124