‘error 99’ read the message on the back of the Canon 400D display (LCD monitor) when using the Canon EFS 17-85mm lens. This camera worked fine with other lenses so we concluded that it was the 17-85mm that had the problem. Advice given on camera display: Turn power switch off and on again or re-install… Read More Fixed: error 99 with Canon EFS 17-85mm 🙂