Ann, a network technician, has just installed a fiber switch in a datacenter. To run the fiber cabling, Ann plans the cable route over the top of the rack using the cable trays, down to the switch, coiling up any excess cable. As Ann configures the switch, she notices several messages in the logging buffer stating the receive signal of the SFP is too weak. Which of the following is MOST likely the cause of the errors in the logging buffer?