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     150260   1. {main}() /var/www/chemiewerkt/index.php:0
    0.3259    5834544   2. SJB_Request->execute() /var/www/chemiewerkt/index.php:81
    0.3259    5834992   3. SJB_System::getPage() /var/www/chemiewerkt/system/core/Request.php:212
    0.3262    5848060   4. SJB_PageConstructor::getPage() /var/www/chemiewerkt/system/core/System.php:331
    0.3356    6191656   5. SJB_System::executeFunction() /var/www/chemiewerkt/system/core/PageConstructor.php:43
    0.3356    6191680   6. SJB_ModuleManager->executeFunction() /var/www/chemiewerkt/system/core/System.php:189
    0.3384    6278392   7. SJB_Classifieds_SearchResults->execute() /var/www/chemiewerkt/system/core/ModuleManager.php:141
    0.3438    6615408   8. SJB_SearchResultsTP->getChargedTemplateProcessor() /var/www/chemiewerkt/system/user-scripts/classifieds/search_results.php:169
    0.3464    6638368   9. SJB_SearchResultsTP->_getListingSidCollectionFromRequest() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:92
    0.4166    7998804  10. SJB_SearchFormBuilder::extractCriteriaFromRequestData() /var/www/chemiewerkt/system/user-scripts/classifieds/SearchResultsTP.php:447
    0.4219    8328844  11. SJB_ObjectProperty->isComplex() /var/www/chemiewerkt/system/lib/classifieds/SearchEngine/SearchFormBuilder.php:124