SQL & PL/SQL

I have a query like this

SQL> SELECT DISTINCT  ASAP.SPEC_REL.ITEM_SPEC_ID_DWN

  2                     FROM ASAP.SPEC_REL

  3                     WHERE LEVEL >= 0

  4                     START WITH ASAP.SPEC_REL.ITEM_SPEC_ID_DWN = 1059

  5                     CONNECT BY   PRIOR ASAP.SPEC_REL.ITEM_SPEC_ID_DWN =  ASAP.SPEC_REL.ITEM_SPEC_ID_UP AND

  6                                                             ASAP.SPEC_REL.ITEM_SPEC_ID_DWN <>  ASAP.SPEC_REL.ITEM_SPEC_ID_UP

  7                     ORDER BY ASAP.SPEC_REL.ITEM_SPEC_ID_DWN DESC;

                        ORDER BY ASAP.SPEC_REL.ITEM_SPEC_ID_DWN DESC

                                 *

ERROR at line 7:

ORA-00904: "ASAP"."SPEC_REL"."ITEM_SPEC_ID_DWN": invalid identifier

But the column exists in the table

SQL> desc ASAP.SPEC_REL

Name                                      Null?    Type

----------------------------------------- -------- ----------------------------

ITEM_SPEC_ID_UP                           NOT NULL NUMBER(9)

ITEM_SPEC_ID_DWN                          NOT NULL NUMBER(9)

INCLUDE_NBR_DWN_IND                                CHAR(1)

LAST_MODIFIED_DATE                        NOT NULL DATE

LAST_MODIFIED_USERID                      NOT NULL VARCHAR2(8)

ORDER_OF_ENTRY                                     NUMBER(3)

If i remove the user.table(asap.spec_rel)  from the query, it works fine.

SQL> SELECT DISTINCT  ITEM_SPEC_ID_DWN
  2                     FROM ASAP.SPEC_REL
  3                     WHERE LEVEL >= 0
  4                     START WITH ITEM_SPEC_ID_DWN = 1001
  5                     CONNECT BY   PRIOR ITEM_SPEC_ID_DWN =  ITEM_SPEC_ID_UP AND
  6                                                             ITEM_SPEC_ID_DWN <>  ITEM_SPEC_ID_UP
  7                     ORDER BY ITEM_SPEC_ID_DWN DESC;

ITEM_SPEC_ID_DWN
----------------
            1008
            1001

I find this error occurs only when using connect by clause.

SQL> SELECT DISTINCT  ASAP.SPEC_REL.ITEM_SPEC_ID_DWN
  2                     FROM ASAP.SPEC_REL;

ITEM_SPEC_ID_DWN
----------------
            1000
            1001
            1002
            1003
            1004
            1005

Also this issue occurs only in test database but works fine in development database;
--in development database

SQL> SELECT DISTINCT  ASAP.SPEC_REL.ITEM_SPEC_ID_DWN
  2                     FROM ASAP.SPEC_REL
  3                     WHERE LEVEL >= 0
  4                     START WITH ASAP.SPEC_REL.ITEM_SPEC_ID_DWN = 1001
  5                     CONNECT BY   PRIOR ASAP.SPEC_REL.ITEM_SPEC_ID_DWN =  ASAP.SPEC_REL.ITEM_SPEC_ID_UP AND
  6                                                             ASAP.SPEC_REL.ITEM_SPEC_ID_DWN <>  ASAP.SPEC_REL.ITEM_SPEC_ID_UP
  7                     ORDER BY ASAP.SPEC_REL.ITEM_SPEC_ID_DWN DESC;

ITEM_SPEC_ID_DWN
----------------
            1001

Please give me the solution or cause for this situation.