Do you have a PP business account?  i have set up a few sites with the new PP and never come across this error before??

Yes I have signed up for new PP

Thats very strange, as it is a fairly straightforward set up, and errors usually happen once accounts are connected??

So you think I'm already connected?

I would log out of software, and log back in, and try again,    screen should look like below  with a merchant account number -

try switching off any antivirus/firealls as well.  Sometimes i cannot preview my websites as antivirus does not allow  webx5 to preview  for some reason??

Hello. I sent a notification about your question to the company employees, expect an answer from them here in the comments.

Hello Graeme

Such an issue seems caused by some issue on PayPal's system

Can you please try to contact them directly and ask them to verify the situation on their system for your account? they can probably verify this for you

Proceed like this and keep me posted on the result

Thank you

Stefano