Can u please say where i am making an error

Contents of a.sql

connect system/manager
select sysdate from dual;
exit ;

trying to logon and execute the scripts


C:\>sqlplus /nolog @a.sql
SP2-0640: Not connected
Connected.

SYSDATE
---------
24-DEC-01

Disconnected from Oracle9i Enterprise Edition Release 9.0.1.1.1 - Production
With the Partitioning option
JServer Release 9.0.1.1.1 - Production