Networking :: SSH Chaining (tunnelling) With Public Keys

I've been searching for a while in forums about the issue I'm facing but couldn't find anything clear, or at least my net search skills are pretty lame. I'm facing a problem with prompted user password in a SSH chain connection when using authorized_keys.

I have: (1) Client - (2) Server - (3) Testing machine (testing machine is connect to Server via usb network)I've created keys for Client and Server, and updated authorized_keys in host machines with the key values: Testing machine has Server public key, and Server has Client public key.Until now everything is fine, if I try to connect via ssh the user password prompt is not shown since public key is found in authorized_keys.

For example: from Client: Code: ssh server Works fine, no password prompt.from Server: Code: ssh testing_machine Works fine, no password prompt.But if try to do that from Client only: from Client: Code: client:$ ssh server Works fine, no password prompt.from Client: Code: server:$ ssh testing_machine Asks for password.Bellow the verbose output from previous ssh command:

Code: ssh -v root(at)192.168.100.2
OpenSSH_5.3p1 Debian-3ubuntu4, OpenSSL 0.9.8k 25 Mar 2009
debug1: Reading configuration data /etc/ssh/ssh_config
debug1: Applying options for *
debug1: Connecting to 192.168.100.2 [192.168.100.2] port 22.
[Code].....