Horn Doesn't Work on my Picasso W Reg 2.0lte Diesel?

My Horn Doesn't work on my Xsara Picasso . Everything else works on the stalk . It may be the fuse but i can't find the fuse position in the fuse Box . It doesn't show up in the manual and doesn't give me fuse no or amps for the fuse . I understand its the fuse box under the bonnet . Can anyone help.