SFTP on AIX 5.2.2

Hello,

On my test host I've installed the SSH soft. Created the Public & Private key for sftp and all works fine. Now I want to modify my scheduled scripts, that runs in batch mode, to work automatically. How can I bypass the Passphrase request when I start my sftp connection.
I modified the /etc/ssh/ssh_config (no config is present in the root home $HOME/.ssh/config) as follow:
Host *
# ForwardAgent no
# ForwardX11 no
# RhostsRSAAuthentication no
# RSAAuthentication yes
# PasswordAuthentication yes
# HostbasedAuthentication no
BatchMode yes
# CheckHostIP yes
# AddressFamily any
# ConnectTimeout 0
# StrictHostKeyChecking ask
# IdentityFile ~/.ssh/identity
# IdentityFile ~/.ssh/id_rsa
# IdentityFile ~/.ssh/id_dsa
# Port 22
# Protocol 2,1
# Cipher 3des
# Ciphers aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,arcfour,aes192-cbc,aes2
56-cbc
# EscapeChar ~

Than I've created a simply text file:
> cat mytestfile
cd ECB
dir
bye
>

Then in my script I do the following call:
#
echo "Start file transfer"
sftp -b mytextfile myuser@domainxxxx.com
#
date
echo "End file transfer"
#

BUT it doesn't work; see the ouput:

+ date
+ echo Start file transfer
+ sftp -b mytextfile myuser@domainxxxx.com
Permission denied (publickey).
Connection closed
+ date
+ echo End file transfer
+ exit

================================================
Could anyone help me ?????
Thanks

What happens when (logged in as root) you perform an ssh hostname? Does it ask for a password? If yes perform an ssh-keygen on the source machine and copy this into the .ssh/authorised_keys on the destination machine in the root directory.