oracle datafile offline drop

[root@hp6200 tmp]#   su - oracle
[oracle@hp6200 ~]$
[oracle@hp6200 ~]$
[oracle@hp6200 ~]$ sqlplus /nolog
                                                                                
SQL*Plus: Release 9.2.0.4.0 - Production on Mon May 5 10:37:03 2008
                                                                                
Copyright (c) 1982, 2002, Oracle Corporation.  All rights reserved.
                                                                                
SQL> connect /as sysdba
Connected.
SQL>
SQL>
SQL>
SQL> alter database datafile '/data1/soft/owprojects/TEST02003066518A.dbs' offline drop;
                                                                                
                                                                                
SQL> shutdown immediate;
ORA-01109: database not open
 
 
Database dismounted.
ORACLE instance shut down.
SQL> startup mount;
ORACLE instance started.
 
Total System Global Area  303633588 bytes
Fixed Size                   451764 bytes
Variable Size             167772160 bytes
Database Buffers          134217728 bytes
Redo Buffers                1191936 bytes
Database mounted.
SQL> alter database datafile '/data1/soft/owprojects/TEST02003066518A.dbs' offline drop;
 
Database altered.
 
SQL> alter database open;
alter database open
*
ERROR at line 1:
ORA-01157: cannot identify/lock data file 15 - see DBWR trace file
ORA-01110: data file 15: '/data1/soft/owprojects/LIUWEIYONG0492543972A.dbs'
 
 
SQL> alter database datafile'/data1/soft/owprojects/LIUWEIYONG0492543972A.dbs' offline drop;
 
Database altered.
 
SQL> alter database open;
 
Database altered.
 
SQL> quit
Disconnected from Oracle9i Enterprise Edition Release 9.2.0.4.0 - Production
With the Partitioning, OLAP and Oracle Data Mining options
JServer Release 9.2.0.4.0 - Production
[oracle@hp6200 ~]$