Error with pyodbc.connect

I have some databases to which I want to connect via pyodbc, if I enter the code:

import pyodbc
pyodbc.dataSources()

I get the following:

    Out[28]: 
{'dBASE Files': 'Microsoft Access dBASE Driver (*.dbf, *.ndx, *.mdx)',
 'Excel Files': 'Microsoft Excel Driver (*.xls, *.xlsx, *.xlsm, *.xlsb)',
 'MS Access Database': 'Microsoft Access Driver (*.mdb, *.accdb)',
 'bdicent': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'troya': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'bdicred': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'bdisolicitud': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'bd_reportos': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'bd_prendarios': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'bd_credito2': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'bdigaran': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'dbterfin': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'bd_garantias_liq': 'IBM INFORMIX ODBC DRIVER (64-bit)',
 'Visio Database Samples': 'Microsoft Access Driver (*.mdb, *.accdb)',
 'bdsolicitud': 'IBM INFORMIX ODBC DRIVER (64-bit)'}

But when I try to connect to a particular DNS an error is generated that I could not solve:

con=pyodbc.connect('DNS=bd_reportos')

Traceback (most recent call last):

  File "<ipython-input-29-27f04177a1ab>", line 1, in <module>
    con=pyodbc.connect('DNS=bd_reportos')

InterfaceError: ('IM002', '[IM002] [Microsoft][Administrador de controladores ODBC] No se encuentra el nombre del origen de datos y no se especificó ningún controlador predeterminado (0) (SQLDriverConnect)')

Could someone give me some idea of what I'm doing wrong?

• I already tried to enter the UID and PWD
• I already changed the version from 64 to 32 bits

HELP !!!