Adding a CS to existing VNX Unified array

I hope someone has run into this issue in the past and can provide a little guidance here...

I'm trying to add a new CS (CS1) to an existing VNX5700 Unified array that has only CS0. It is running 7.1.80.3 code.

I got the procedure on Solve and went through using the Express DVD on CS1. The first 32 tasks went fine, and then on the last task - "set up ssh keys", it fails with this:

Host key verification failed.

Error: 255

Error IM_14505280158 : Non interactive SSH communication failed to

         establish from peer to standby Control Station.

Description:

        SSH communication failed.

Action : Do the following to help investigate the issue:

         1) Run "/nasmcd/nas_mcd -e emcnasotherCS_i0 check_ssh_connection"

            command. If the command succeeds with return status 0, then retry

            the upgrade; else go to step 2.

         2) If the problem persists or you need assistance, escalate to your

            support organization with the failure details.

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Now CS1 shows reason code 6. Anybody has any idea on how to fix this??? I'm stuck!

Thanks in advance.

James