Cannot get a backup using a script

I have been trying to get automated backups of a PostgreSQL database using
a script without success. The error I get is "fe_sendauth: no password
supplied".

I have a pgpass.conf in
"C:\Users\Username\AppData\Roaming\postgresql\pgpass.conf" with the correct
information: localhot:5432:dbname:postgres:mypassword

The script I am testing is as follows:
pg_dump -E win1252 -f d:/respaldos/edocuments/edoc.backup -F p -n
edocuments -h localhost -U postgres -w edocuments

I have run such a script with -W instead of -w just to test and I am asked
for password and it runs correctly, so the script is fine I suppose.

I also added the following line to the script and I get the same error
message:
SET PGPASSFILE="C:\Users\Username\AppData\Roaming\postgresql\pgpass.conf"

My OS is Windows Server 2008 R2.

I will very much appreciate any help.

With respect,
Jorge Maldonado