problem using Net::SFTP with pubkey

i've got a problem using Net::SFTP [which uses Net::SSH::Perl] - i've
install some existing script
which worked fine for me and installed on a new server [with fresh
version of Net::SSH::Perl]

this script is downloading a file via SFTP using pubkey authorization -
but for some reason i get smth like connection broken:

(here is what i get with debug=1)

processing ns_4
Downloading __SERVER_IP//home/plain_stats at ./get_ssh.pl line 158.
Net::SFTP from ns_4
RH9-3: Reading configuration data /root/.ssh/config
RH9-3: Reading configuration data /etc/ssh_config
RH9-3: Allocated local port 1023.
RH9-3: Connecting to 64.27.7.144, port 22.
RH9-3: Remote protocol version 1.99, remote software version
OpenSSH_3.5p1
RH9-3: Net::SSH::Perl Version 1.26, protocol version 2.0.
RH9-3: No compat match: OpenSSH_3.5p1.
RH9-3: Connection established.
RH9-3: Sent key-exchange init (KEXINIT), wait response.
RH9-3: Algorithms, c->s: 3des-cbc hmac-sha1 none
RH9-3: Algorithms, s->c: 3des-cbc hmac-sha1 none
waiting for 22838
RH9-3: Entering Diffie-Hellman Group 1 key exchange.
RH9-3: Sent DH public key, waiting for reply.
RH9-3: Received host key, type 'ssh-dss'.
RH9-3: Host '64.27.7.144' is known and matches the host key.
RH9-3: Computing shared secret key.
RH9-3: Verifying server signature.
RH9-3: Waiting for NEWKEYS message.
RH9-3: Enabling incoming encryption/MAC/compression.
RH9-3: Send NEWKEYS, enable outgoing encryption/MAC/compression.
RH9-3: Sending request for user-authentication service.
RH9-3: Service accepted: ssh-userauth.
RH9-3: Trying empty user-authentication request.
RH9-3: Authentication methods that can continue:
publickey,password,keyboard-interactive.
RH9-3: Next method to try is publickey.
RH9-3: Trying pubkey authentication with key file '/root/.ssh/id_dsa'
RH9-3: Login completed, opening dummy shell channel.
RH9-3: channel 0: new [client-session]
RH9-3: Requesting channel_open for channel 0.
RH9-3: channel 0: open confirm rwindow 0 rmax 32768
RH9-3: Got channel open confirmation, requesting shell.
RH9-3: Requesting service shell on channel 0.
RH9-3: channel 1: new [client-session]
RH9-3: Requesting channel_open for channel 1.
RH9-3: Sending subsystem: sftp
RH9-3: Requesting service subsystem on channel 1.
RH9-3: channel 1: open confirm rwindow 0 rmax 32768
RH9-3: sftp: Sending SSH2_FXP_INIT
RH9-3: sftp: Remote version: 3
RH9-3: sftp: Sent message T:17 I:0
RH9-3: sftp: Received stat reply T:105 I:0
RH9-3: sftp: Sent SSH2_FXP_OPEN I:1 P:/home/plain_stats
Error from __SERVER_IP: input must be 8 bytes long at
/usr/lib/perl5/site_perl/5.8.0/i386-linux-thread-multi/Crypt /DES.pm
line 57.


and on the server side in /var/log/secure i have


Aug 31 17:00:27 cp4 sshd[1771]: Accepted publickey for root from
__CLIENT__IP____ port 1023 ssh2
Aug 31 17:00:28 cp4 sshd[1771]: subsystem request for sftp


anything wrong? what could i miss in server/client SSH configuration?