Why is my PayPal account showing as inactive on my store's payment methods?

Hey,

I’m just launching my store, I had a standard paypal account when I joined Shopify and set up my payment methods. Later on I upgraded paypal to a business account.
But now when I look at my payment methods it appears as inactive.

When I click “Activate paypal express” I get the following message:

How can I overcome this issue?