Switchover to Standby instance : Dataguard 11gR2

DGMGRL> switchover to TESTMP2;
Performing switchover NOW, please wait...
Error: ORA-16627: operation disallowed since no standby databases would remain to support protection mode

Failed.
Unable to switchover, primary database is still "TESTMP1"
DGMGRL> edit database TESTMP1 set property
> 'LogXptMode'='SYNC';
Property "LogXptMode" updated
DGMGRL> switchover to TESTMP2;
Performing switchover NOW, please wait...
New primary database "TESTMP2" is opening...
Operation requires shutdown of instance "TESTMP1" on database "TESTMP1"
Shutting down instance "TESTMP1"...
ORA-01031: insufficient privileges

Warning: You are no longer connected to ORACLE.

Please complete the following steps to finish switchover:
        shut down instance "TESTMP1" of database "TESTMP1"
        start up instance "TESTMP1" of database "TESTMP1"

DGMGRL> exit