Why is "Confirm Payment" gray'd out?

I've installed the PayPal PayFlow Gateway... entered my transaction information... purposely made a mistake entering CC info... it caught that. Entered the right stuff... it lit up the VISA icon, that's correct... a VISA card... put in the rest of the stuff... but the button that says, "Confirm Payment" remains grayed out. I can click it and it runs through speaking with the server... and comes back to the same page.
I have the transaction going to the Sandbox... the URL says it's SSL: https://www.newmexicovideo.com/store/shopping-cart/confirm-checkout/

So why is it not completing the transaction?