how to troubleshooting the issue about Gather Schema Statistics

Hi Experts

we did the following test about Gather Schema Statistics

1. First run the two SQL

select OWNER,TABLE_NAME,LAST_ANALYZED from dba_tables where TABLE_NAME like 'DR%' and OWNER ='PA';

set pagesize 1600
SELECT DISTINCT C5, C1, D1
FROM FND_STATTAB
WHERE 1=1
AND TYPE = 'T'
AND C5 IN ('PA')
ORDER BY C5, C1;

2.run  Gather Schema Statistics with parameter (PA,25,BACKUP LASTRUN,GATHER) in R11i environment

3.After complete successfully,run the two SQL again,and we found the value of  LAST_ANALYZED  for the tables which begin with DR$

  has been updated,but In FND_STATTAB tables, we can not found the backup data for