Originally Posted by danpeake

You need to swipe your card and hit cancel/change payment before the cashier gets to the payment screen. You can ask them to wait to hit the card payment button until after you've swiped. "It worked before if I swipe it first."

Originally Posted by mcgyvr116

You: I would like to add money to my debit card (Amex BB)
Cashier: Swipe your card. How much?
You: *Tell cashier amount*
Cashier: Confirm amount on the screen
You: Swipe MCGC and wait for 'cancel' to blink on screen. It will blink once and it will be quick so pay attention. After it blinks, press cancel and it will take you to a change payment screen. Select Debit. Payment should go through.

If not, try again. I have had success at MC and Cashier. Sometimes it takes 2-3 times.

*Sometimes it helps if you ask cashier to wait until after you swipe to hit debit. Also if you ask cashier to hit debit on the keypad instead of the touchscreen the success rate is much higher. Speaking from experience, YMMV.