connect as sysasm

Here is using AIX and having a OS user , for example testing

testing is in OS group dba, oinstall

Here I want to connect to ASM using

sqlplus / as sysasm

it says

ERROR:

ORA-01017: invalid username/password; logon denied

However, when using sqlplus / as sysdba from same OS user testing there is no problem

Password file is list below

ASMCMD> lspwusr

        Username sysdba sysoper sysasm

             SYS   TRUE    TRUE   TRUE

CRSUSER__ASM_001   TRUE   FALSE   TRUE

         ASMSNMP   TRUE   FALSE  FALSE

What's the problem I have here ??

Database version 12.2 , AIX 7.1