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
    0.4362    5830580   2. SJB_Request->execute() /var/www/chemiewerkt/index.php:81
    0.4362    5831028   3. SJB_System::getPage() /var/www/chemiewerkt/system/core/Request.php:212
    0.4365    5844096   4. SJB_PageConstructor::getPage() /var/www/chemiewerkt/system/core/System.php:331
    0.4438    6187668   5. SJB_System::executeFunction() /var/www/chemiewerkt/system/core/PageConstructor.php:43
    0.4438    6187692   6. SJB_ModuleManager->executeFunction() /var/www/chemiewerkt/system/core/System.php:189
    0.4465    6274408   7. SJB_Classifieds_SearchResults->execute() /var/www/chemiewerkt/system/core/ModuleManager.php:141
    0.4517    6611404   8. SJB_SearchResultsTP->getChargedTemplateProcessor() /var/www/chemiewerkt/system/user-scripts/classifieds/search_results.php:169
    0.4542    6634360   9. SJB_SearchResultsTP->_getListingSidCollectionFromRequest() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:92
    0.5700    7983540  10. SJB_SearchFormBuilder::extractCriteriaFromRequestData() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:447
    0.5750    8313692  11. SJB_ObjectProperty->isComplex() /var/www/chemiewerkt/system/lib/classifieds/SearchEngine/SearchFormBuilder.php:124