Cards can be declined for any number of reasons!

The easiest thing to do is to head to https://account.betterworld.org/settings/cards and retry the charge manually there (or click the link in the email you would have received).

You can use a new or an existing card, and you'll see if the charge was successful right there on the screen. Once you do that, the payment status will automatically update for you and for the nonprofit as well.