TABLESPACE creation error I have an error "ORA-01537" when I create a tablespace.

create tablespace "VOLUMT" datafile 'VOLUMT.dbf' size 250M autoextend on;


Then, it shows like following.


  ERROR at line 1: ORA-01537: cannot add file 'VOLUMT.dbf' - file
  already part of database


I just change the tablespace name of VOLUMT to TEST01, and it works..


  Tablespace created.


So, I get into the directory of db and searched the related tablespace..

${HOME}/oracle/db/oradata/ORAC12


However, I can't find any.. Coudl you help me to solve this problem? Also I need to use "VOLUMT" for tablespace creation.. not TEST01..

-- Additional -- 


select TABLESPACE_NAME from DBA_DATA_FILES;

TABLESPACE
----------
SYSTEM
SYSAUX
USERS
TEST01


I can see TEST01 Tablespace, but I can't find any datafiles in the directory.
Also I can't find any VOLLMT tablespace in it..

Thank you.
all the guys..

First of all, really appreciate to you all for replying...

When I input the follwing


select   file_name,
         file_id,
         tablespace_name,
         status,online_status 
from     dba_data_files 
order by tablespace_name;


The output is 


FILE_NAME
--------------------------------------------------------------------------------
   FILE_ID TABLESPACE STATUS    ONLINE_
---------- ---------- --------- -------
/home/oracle/db/oradata/ORAC12/ID/sysaux01.dbf
    28 SYSAUX     AVAILABLE ONLINE

/home/oracle/db/oradata/ORAC12/ID/system01.dbf
    27 SYSTEM     AVAILABLE SYSTEM

/home/oracle/db/oradata/ORAC12/ID/ID_user01.dbf
    29 USERS      AVAILABLE ONLINE


There is no such as "VOLUMT" tablespace. When I re-try to create a "TEST01" tablespace, eventhough it's already deleted, it shows 'the file exists already'..

When I get into the directory, there are other SID's as well. And, one of them has "VOLUMT". However, they are different "SID" so they can have same name of tablespace, isn't it?