Can't link device to Remote ID

Hi. I have a Pro and an Ultra 4. Both sitting on my home LAN at the moment, but eventually one will be remote. Both working fine. Both have current versions of Remote and Replicate installed.

I have registered the Pro and linked it to my readynas remote id without a hitch. But trying to do the same with the Ultra 4 I get an error message: "ReadyNAS Replicate could not register [my_Remote_id] user. Please check user name and password. If the ReadyNAS is behind an HTTP proxy, please make sure you have entered correct proxy server settings."

I've checked my typing skills several times and am very confident I'm putting in the right password. :D

What am I missing?

Thanks.

PS I'm using the same Remote ID for both NAS's. Is that right?