When you process a payment, if you or your client sees the notification "Transaction Failed", this means that your payment provider has not processed the transaction for you.
WHAT DO I DO
You should login to your payment provider account/dashboard, maybe Stripe or Authorize.net, and see what reason was given for the transaction failure.
If it is not obvious what the reason is, you should make direct contact with your payment provider by phone/email.
Once you know the reason, and the matter resolved, you should try processing the payment again.
PAYMENT PROVIDER DASHBOARD LINK
There is a link to your payment provider dashboard in Settings - Payments. Image below is for an account with a Stripe integration. This can only be accessed by your team, BriteVenue support members do not have authorization to access your payments account.
NOTE - Only users that have permissions to Settings - Payments will have access to this area of BriteVenue.