SunOS 5.8 sftp-BatchMode Problem

Hi Gurus

I have to connect from a SunOS 5.10 to a 5.8 using sftp in BatchMode. For this, I have generated a Public-Key (ssh-keygen -b 1024 -P "" -t dsa) on the 5.10 and saved it in ~remote-user/.ssh/authorized-keys on the 5.8.

Then, running either one of ssh or sftp, it asks for the remote-user's password!!

For your added information, as you might already know, the above procedure works fine when going from 5.10 to 5.10.

Can you please tell me what am I missing here?
With my greatest appreciations,
unilover