SQL & PL/SQL

Hi,
in following query Itried to format End_time to show the hour in addition to date. But I have an ERROR: ORA-01722.

SELECT j.job_name, j.job_owner, j.job_id, j.job_type,
e.execution_id, e.scheduled_time,
e.start_time + t.timezone_delta / (60 * 24) start_time,
to_char(e.end_time,'DD-MON-RR HH:MI AM') + t.timezone_delta / (60 * 24) end_time,
DECODE( e.status,
1, 'Scheduled',
2, 'Running',
3, 'Failed Initialization',
4, 'Failed',
5, 'Succeeded',
6, 'Suspended By User',
7, 'Suspended: Agent Unreacheable',
8, 'Stopped',
9, 'Suspended on Lock',
10, 'Suspended on Event',
11, 'Stop Pending',
13, 'Suspend Pending',
14, 'Inactive',
15, 'Queued',
16, 'Failed Retried',
18, 'Skipped',
e.status) status,
t.target_name, t.target_type, t.target_guid
FROM MGMT_JOB j, MGMT_JOB_EXEC_SUMMARY e, MGMT_JOB_TARGET jt, MGMT_TARGETS t
WHERE j.job_id=e.job_id AND
e.job_id=jt.job_id (+) AND
e.execution_id=jt.execution_id (+) AND
jt.target_guid=t.target_guid (+) AND
j.job_name like '%SYSADM%';

Thanks for your help.