Mr. Luigi issued a check drawn against ABC Bank in favor of Mr. Yen as payment for certain shares of stocks which he purchased. On the same day that he issued the check to Mr. Yen, Mr. Luigi ordered ABC Bank to stop payment. Per standard banking practice, Mr. Luigi was made to sign a waiver of ABC Bank's liability in the event that it should pay Mr. Yen through oversight or inadvertence. Despite the stop payment order by Mr. Luigi, ABC Bank nevertheless paid Mr. Yen upon presentation of the check. Mr. Luigi sued ABC Bank for paying against his order. Is ABC Bank liable? Explain.