RMAN tablespace restore fails with error - "ORA-01109: database not open". (4046555)

Date - 12/2009
Affected Product & Version - NetVault: Backup 7.4.5 and later
Affected Module & Version - APM for Oracle (Version 5.5) and later
OS Version - All
Application Information - Oracle 9.2.x/10.1.x/10.2.x/11.1.x


Description:
RMAN tablespace restore fails with error - "ORA-01109: database not open".


Symptoms:
When restoring tablespace with RMAN using "Alter Tablespaces Offline Before Restore" option selected, restore fails with "ORA-01109: database not open" error.

RMAN> run {
2> allocate channel nvch1 type 'SBT_TAPE';
3> sql "alter tablespace USERS offline immediate";
4> restore datafile 4 until scn 1546350 ;
5> release channel nvch1;
6> }
7>
allocated channel: nvch1
channel nvch1: sid=154 devtype=SBT_TAPE
channel nvch1: NetVault Oracle APM v.5.5.11
sql statement: alter tablespace USERS offline immediate
released channel: nvch1
RMAN-00571: ===========================================================
RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============
RMAN-00571: ===========================================================
RMAN-03009: failure of sql command on default channel at 11/16/2009 16:21:02
RMAN-11003: failure during parse/execution of SQL statement: alter tablespace USERS offline immediat...
ORA-01109: database not open
Recovery Manager complete.
Failed with exit code 1
RMAN returned exit code 1