Getting error on Production system ora-00904 invalid identifier

Hi All,

I am getting error ORA-00904 on production system for following query

the following query executes without error on My development system.

select (select status_name
                 from (select Status_Name from v_aso_status
                                          where agency_id = ag.agency_id -- Here it gives erro ag.agency_id invalid identifier.
                                           AND STAGE_CODE = 'I'
                                           order by status_id desc)
         where rownum = 1) AS "INSPECTION STATUS"
       from v_Agencies ag
       where  ag.AGENCY_CLASS = 'Passenger'
              And (ag.Application_Type_Name = 'NEW APPLICATION'
              And  ag.aims_date is not null
              or   ag.Application_Type_Name = 'CHANGE REQUEST'
              OR   ag.Application_Type_Name = 'MISCELLANEOUS')

what to check on development and production system?

Development server is Windows 10g database and Production is AIX 5.3 Oracle 10g database.

All tables and columns are present on both the system.

-- Suresh Borse