I have been interested in photography for years and previously had Nikon film SLR's. A few years ago I moved into digital and went for the Canon 300d (Rebel) as it got a good review at the time and was a lot lighter that the Nikon. As I am getting on a bit now I wanted to reduce the weight of my camera bag. I have a question from the off if that is OK. I have just bought a Canon 450d (Rebel Xsi) with 18-55 IS lens. All seems OK apart from the fact that I can't seem to get the AF to work apart from Auto and programme modes. It will not work in P,Tv,Av,or M. I have tried all I can but am probably missing something. Can someone put me out of my misery please?