Why is my payment method not accepting my card

Not all debit cards are accepted. Then you try to add the card, what error message do you get? Declined?

See the Apple Support article(s) below. Link to contact Apple Support in the article. 

Apple ID payment information - If your payment method is declined, or you have a billing issue with a previous purchase in the iTunes Store.    

Possible fixes.   Fix ‘Your Payment Method Was Declined’ Error In App Store

                          Payment method declined in iTunes or the App Store.