SQL & PL/SQL

Hi,

I have a simple bit of SQL to pull out details about supervisor chains in HR in Oracle EBS:

SELECT     LPAD(' ', (LEVEL - 1) * 10, ' ') || person_id level_label
         , LEVEL
         , description
      FROM applsys.fnd_user u
         , hr.per_all_assignments_f h
     WHERE u.employee_id = h.person_id
START WITH SYSDATE BETWEEN effective_start_date AND effective_end_date
       AND person_id = :personid
CONNECT BY PRIOR person_id = supervisor_id
       AND SYSDATE BETWEEN effective_start_date AND effective_end_date

It'll normally return data without a problem - e.g. dummy data below - looks fine. Names and person_ids made up.

LEVEL_LABEL				LEVEL	DESCRIPTION
000001					1	Person Person 1
          000002			2	Harry Marry
                    000003		3	John Smith
                              000004	4	Jenna Jones
                              000005	4	Her Name
                              000006	4	His Name
                              000007	4	Joseph Coat
                              000008	4	Les Miserables
                    000009		3	Mister Smith
                    000010		3	Miss Jones
                    000011		3	Andrew And
                              000012	4	Claire So
                              000013	4	Hilary Hi
          000014			2	Jenny Jones
                    000015		3	Amanda Mandy
                              000016	4	James Jim
                              000017	4	William Wonder
                              000018	4	Crazy Cat
                              000019	4	Silly Cat
                              000020	4	Tall Hill
                              000021	4	Amazing Grace
                    000022		3	Lovely Mountain
                              000023	4	Joyous Spring
                              000024	4	Anonymous Name
                              000025	4	Brian Binky

However, if I try for another person_id, for which a user is getting an error in part of Oracle EBS, I get this error:

ORA-01436: CONNECT BY loop in user data

I'm guessing there is a supervisor loop happening somewhere, but I don't know how to investigate where it might be happening.

I wondered if there is any way I can modify the SQL to be able to work out where the loop might be, as there are about 50 staff involved in the dept. for this user and I have been through all of their records and can't see a loop from looking through the Oracle HR screens.

I know it's a "big ask", to ask a vague question about some oracle SQL, so apologies for that.

Any advice much appreciated.

Thanks