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:
    0.0006     150264   1. {main}() /var/www/chemiewerkt/index.php:0
    0.1260    5905100   2. SJB_Request->execute() /var/www/chemiewerkt/index.php:81
    0.1260    5905548   3. SJB_System::getPage() /var/www/chemiewerkt/system/core/Request.php:212
    0.1263    5918616   4. SJB_PageConstructor::getPage() /var/www/chemiewerkt/system/core/System.php:331
    0.1338    6262276   5. SJB_System::executeFunction() /var/www/chemiewerkt/system/core/PageConstructor.php:43
    0.1338    6262300   6. SJB_ModuleManager->executeFunction() /var/www/chemiewerkt/system/core/System.php:189
    0.1366    6349036   7. SJB_Classifieds_SearchResults->execute() /var/www/chemiewerkt/system/core/ModuleManager.php:141
    0.1427    6686124   8. SJB_SearchResultsTP->getChargedTemplateProcessor() /var/www/chemiewerkt/system/user-scripts/classifieds/search_results.php:169
    0.1454    6709212   9. SJB_SearchResultsTP->_getListingSidCollectionFromRequest() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:92
    0.1878    7977832  10. SJB_SearchFormBuilder::extractCriteriaFromRequestData() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:447
    0.1949    8307684  11. SJB_ObjectProperty->isComplex() /var/www/chemiewerkt/system/lib/classifieds/SearchEngine/SearchFormBuilder.php:124