isqlplus 10g

hi all
i am unable to connect to isqlplus

when i entered
usr sys as sysdba
pwd ****
conn identifer : db3 ( database name)

its throwing error as
SP2-0306 - Invalid option. Usage: CONN[ECT] username/ password[@connect_identifier] [AS {SYSOPER|SYSDBA}] or: CONN[ECT] / [@connect_identifier] AS {SYSOPER|SYSDBA

can any one help me out
from
Harish Received on Tue Dec 11 2007 - 07:12:19 CST