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     150760   1. {main}() /var/www/chemiewerkt/index.php:0
    0.2201    5834084   2. SJB_Request->execute() /var/www/chemiewerkt/index.php:81
    0.2201    5834532   3. SJB_System::getPage() /var/www/chemiewerkt/system/core/Request.php:212
    0.2203    5847600   4. SJB_PageConstructor::getPage() /var/www/chemiewerkt/system/core/System.php:331
    0.2278    6191232   5. SJB_System::executeFunction() /var/www/chemiewerkt/system/core/PageConstructor.php:43
    0.2278    6191256   6. SJB_ModuleManager->executeFunction() /var/www/chemiewerkt/system/core/System.php:189
    0.2305    6277952   7. SJB_Classifieds_SearchResults->execute() /var/www/chemiewerkt/system/core/ModuleManager.php:141
    0.2359    6614996   8. SJB_SearchResultsTP->getChargedTemplateProcessor() /var/www/chemiewerkt/system/user-scripts/classifieds/search_results.php:169
    0.2386    6637952   9. SJB_SearchResultsTP->_getListingSidCollectionFromRequest() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:92
    0.2925    8031184  10. SJB_SearchFormBuilder::extractCriteriaFromRequestData() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:447
    0.2977    8360916  11. SJB_ObjectProperty->isComplex() /var/www/chemiewerkt/system/lib/classifieds/SearchEngine/SearchFormBuilder.php:124