unable to register integrated extract

Our GoldenGate databases are out of sync because some archived logs got deleted. So I re-set up the GoldenGate again.

Here is what I did:

stop extract ext1

detete extract ext1

unregister extract ext1 database

then when I try to

register extract ext1 database

it hangs for a very long time, and finally it gave the error message:

ERROR   OGG-08221  Cannot register or unregister EXTRACT EASEXT because of the following SQL error: OCI Error 4021.

I checked the process, it waits for 'library cache lock'

I check further with this query:

select

     distinct

       ses.ksusenum sid, ses.ksuseser serial#, ses.ksuudlna username,KSUSEMNM module,