PayPal error

Hi,

I installed all the files op de the supporter plugin and that works great.
Finally I set up a paypal subscription.

But when I like to pay with paypal I get the follow error:
"We are unable to modify your subscription. This may be because your existing subscription calls for no more payments to be made or because it has been cancelled or completed."

Note: We have a business paypal subscription for recurring payments.

Do you know what get wrong?

Thank you for your help in advance!

Cheers, Stijn