TOPIC: How to get PayPal to work in DT Register

Hi, nearing completion of DT Register on our new site (really pleased with it so far) and wanting to know how to get PayPal to work. I have actioned the IPN (Instant Payment Notification) in my PayPal account as advised by DT register in the configuration area. I thought this was all I needed to do, but when I do a dummy registration on my site and choose PayPal as the payment method it goes to the PayPal page/site all OK, but then says 'merchant cannot receive money' (or similar). I have a PayPal business account so all should be OK with that.

Maybe there is something else I need to do in PayPal itself ?

Could anyone help please !

Many thanks,
Bax.