ORA-12528 tns listener all appropriate instances are blocking new connections

Got an error ORA-12528 while doing a duplicate in 11gr2 with active database.

Tried below link, but could not succeed

http://osamamustafa.blogspot.in/2012/02/ora-12528-tns-listener-all-appropriate.html


However, fixed it after restarting listener and modifying listener.ora file because of follwoing error:

NSLSNR for Linux: Version 11.2.0.1.0 - Production
System parameter file is /u01/app/home/oracle/product/11.2.0/my_db/network/admin/listener.ora
Log messages written to /u01/app/home/oracle/product/11.2.0/my_db/log/diag/tnslsnr/asus001n2/listener/alert/log.xml
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=10.0.1.11)(PORT=1521)))
Listening on: (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=PNPKEY)))
TNS-01192: Missing SID_LIST_ value left of equation for SID description in LISTENER.ORA

Listener failed to start. See the error message(s) above...