Remote Access Data Transfer Error

We have set up remote access for a client Sage 50 Accounts V28. We've added two new users and set up their remote access. They receive the email and go through the process of entering the passphrase and a Data Transfer error comes up stating the below:

An error was encountered while transferring data for remote Access.

To retry the data transfer, click Retry.

If you want to continue processing data offline, click work offline.

To close Accounts and lose your changes, click Close.

This has happened for both new users. I've deleted the user's and added them again and the same error occurs.

Any advance, greatly received as my own remote access it working and also syncing correctly to their head office Sage.

Many thanks.