> I think that you will need to give more information about the values that
> are used in this query before we can help you.

thanks for the answer Martijn!
The values are

:ID = 1
:ID_EMPRESAS = 1
:NOMBRE = 'PRUEBA'
:DIRECCION = ''
:TELEFONOS = ''

if I remove the "AND (:NOMBRE <> '')" parts the query runs without problem. As this simple query is for cheking if a customer already exist in the database, I don't want to evaluate the blank fields, thats why I added the forementioned part.

Thanks again!!

-s