A system is configured for detecting errors in an ATM. The system includes a processor that receives a withdrawal request from a user to receive cash from a cash dispenser of the ATM. Currency denominations and a number of bills for each currency denomination needed to fulfill the withdrawal request is determined. The system sends signal commands to cassettes of the ATM to dispense bills to fulfill the withdrawal request. A camera is positioned in a pathway of the bills being dispensed from the cassettes to the cash dispenser. The camera captures images of bills being dispensed from the cassettes and sends them to the processor. The processor generates an alert if a number of bills dispensed from at least one cassette does not match a corresponding number of bills expected to be dispensed from the at least one cassette.