すみません、カードが使えません。 — Excuse me, my card isn't working. (Train · Station, Formal — to staff, JLPT N5)

Gesture & etiquette

Point to the IC card reader at the gate or your IC card. Step slightly to the side of the gate to allow others to pass.

Do not force your way through the gate if your IC card doesn't work. Always ask staff for help immediately. If your card has insufficient balance, they will likely tell you to charge it.