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:
    0.0003     150232   1. {main}() /var/www/chemiewerkt/index.php:0
    1.1624    5830556   2. SJB_Request->execute() /var/www/chemiewerkt/index.php:81
    1.1624    5831004   3. SJB_System::getPage() /var/www/chemiewerkt/system/core/Request.php:212
    1.1627    5844072   4. SJB_PageConstructor::getPage() /var/www/chemiewerkt/system/core/System.php:331
    1.2956    6187720   5. SJB_System::executeFunction() /var/www/chemiewerkt/system/core/PageConstructor.php:43
    1.2956    6187744   6. SJB_ModuleManager->executeFunction() /var/www/chemiewerkt/system/core/System.php:189
    1.2988    6274444   7. SJB_Classifieds_SearchResults->execute() /var/www/chemiewerkt/system/core/ModuleManager.php:141
    1.3487    6611476   8. SJB_SearchResultsTP->getChargedTemplateProcessor() /var/www/chemiewerkt/system/user-scripts/classifieds/search_results.php:169
    1.3515    6634540   9. SJB_SearchResultsTP->_getListingSidCollectionFromRequest() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:92
    1.6962    7958488  10. SJB_SearchFormBuilder::extractCriteriaFromRequestData() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:447
    1.7600    8288896  11. SJB_ObjectProperty->isComplex() /var/www/chemiewerkt/system/lib/classifieds/SearchEngine/SearchFormBuilder.php:124