Mysqli prepare error: Unknown column 'obj.GKID2' in 'on clause'

/home/ : 115 : SELECT obj.*, as district, as locality, as street, as `raion`, as `mraion`, as `metro`, as gk, as gk2 FROM HOUSES AS obj LEFT JOIN nmls_ru_mls_city_manage.vocDistrict ON vocDistrict.`id` = obj.DISTRICT_ID LEFT JOIN nmls_ru_mls_city_manage.vocLocality ON vocLocality.`id` = obj.LOCALITY_ID LEFT JOIN nmls_ru_mls_city_manage.vocSubLocality ON = obj.`RAIONID` LEFT JOIN nmls_ru_mls_city_manage.vocStreet ON = obj.`STREETID` LEFT JOIN nmls_ru_mls_city_manage.vocMicro ON vocMicro.`ID` = obj.`MRAIONID` LEFT JOIN nmls_ru_mls_city_manage.vocMetro ON vocMetro.`id` = obj.`METROID` LEFT JOIN nmls_ru_mls_city_manage.vocGk ON vocGk.`id` = obj.`GKID` LEFT JOIN nmls_ru_mls_city_manage.vocGk as vocGk2 ON vocGk2.`id` = obj.`GKID2` WHERE obj.COMPID = '3002823' AND obj.CARDNUM = '2349' AND CSTATUS = 1 AND VARIANT&1 LIMIT 1
/home/ : 381 :
Catchable fatal error: Object of class Zend_Db_Adapter_Mysqli could not be converted to string in /home/ on line 4