Oracle ODBC: works from MS ODBC Admin(32) Test, but ORA-12154 from python

Question

I am trying to connect from Windows Server 2008 R2 to remote Oracle 12. I created tnsnames.ora

 
MY_DSN=
(DESCRIPTION=
   (ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=X.XXX.XX.XX)(PORT=1521)))
    (CONNECT_DATA=(SID=ORASERVER))
) 

I created System DSN using 32 bits ODBC Administrator. There is "Test Connection" button in ODBC arministrator; I used to confirm what connection works.

But I failed to use this DSN from python 3.4.3 Anaconda 2.2 (32 bits)

    import pypyodbc
    cStr = 'DSN=MY_DSN;UID=stranger;PWD=secret'
    conn = pypyodbc.connect(cStr)

I got

pypyodbc.DatabaseError: ('08004', '[08004] [Oracle][ODBC][Ora]ORA-12154: 
TNS:could not resolve the connect identifier specified\n')