In the app check that your card is visible, active and not greyed out. If this is not the case, please check whether the transaction was not blocked due to a set monthly transaction limit in the application. You can check this in the following way: 

Go to "Finances" section in the application-> select the card for which you want to check the limit
-> click on "Settings" -> verify if you have no yet exceeded your monthly transaction limit.
Also, check whether the type of payment (such as contactless and magnetic stripe) are enabled. If everything looks good, we recommend you to click on "Edit" and then save again the limit. 

If the card is still not working please contact us on chat in the application.