I've created a standby database but when I tried to start it up with "ALTER DATABASE MOUNT STANDBY DATABASE", it complains

ORA-01991: invalid password file 'c:\oracle\ora81\DATABASE\PWDtest.ORA'

I checked the file PWDtest.ORA on both Primary and Standby, they look the same. Can I simply copy the PWDtest.ORA from Primary to Standby? I have same password for "internal" on both system. Why it is complaining?