The payment card that is connected to your wearable is connected to the same account as your physical payment card. Make sure that it has enough funds for the transaction.
Use the Fidesmo Android app, iPhone app, our Self Service Portal, or call your banks customer care and verify that the connection between your card and wearable is active. The connection can be put into a suspended state, which prevents payments being made.
Try connecting your payment card to the wearable again, using the Fidesmo Android app.