Problem shutting down physical standby

Hi,

I need your help because  I cannot shutdown a physical standby. The only error arising is

ALTER DATABASE CLOSE NORMAL

ORA-1109 signalled during: ALTER DATABASE CLOSE NORMAL...

I only have 1 database Standby and the Primary.

RECOVERY_MODE is MANAGED REAL TIME APPLY. Database version is 11.2.0.3.0

I am executing:

In Primary

    ALTER SYSTEM ARCHIVE LOG CURRENT;

    SHUTDOWN IMMEDIATE;

In Standby

    ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;

    SHUTDOWN IMMEDIATE;

I will appreciate any comment.

Thanks

Bety