Oracle 11g ASM permission problems

In Oracle 11g, use sysdba to connect to ASM.
SQL> conn/as sysdba
SQL> alter diskgroup DATA mount;
Alter diskgroup DATA mount
*
ERROR at line 1:
ORA-15032: not all alterations saved med
ORA-15260: permission denied on ASM disk group
ORA-15260: permission denied on ASM disk group
Inform the permission to be rejected.
[Root @ rac1 ~] # Su-grid
> $ Sqlplus/as sysdba
SQL * Plus: Release 11.2.0.1.0 Production on Thu May 3 15:28:20 2012
Copyright (c) 1982,200 9, Oracle. All rights reserved.
Connected:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0-64bit Production
With the Real Application Clusters and Automatic Storage Management options
SQL> alter diskgroup webdg add disk '/dev/raw/raw4 ';
Alter diskgroup webdg add disk '/dev/raw/raw4'
*
ERROR at line 1:
ORA-15032: not all alterations saved med
ORA-15260: permission denied on ASM disk group
Use sysasm to connect.
/Home/grid @ serv1 => + ASM1 $ sqlplus/as sysasm
SQL * Plus: Release 11.2.0.1.0 Production on Thu May 3 15:29:42 2012
Copyright (c) 1982,200 9, Oracle. All rights reserved.
Connected:
Oracle Database 11g Enterprise Edition Release 11.2.0.1.0-64bit Production
With the Real Application Clusters and Automatic Storage Management options
SQL> show user
USER is "SYS"

SQL> alter diskgroup DATA mount;
Diskgroup altered.
This is an improvement of 11g in ASM management.