The closed captioning decoder circuit in your TV set may not be working, or the closed captioning information from the station may not be present. Start investigating by finding out if there is actualy closed caption from the station that you are tuned in to. If so, then call the tech support for your set to know if there is something that you missed in the set-up for the closed captioning. It may be very simple. If all of this does not work, then the closed captioning decoder in the set may not be working properly and require service.