FIrst, excuse me for my terrible english.
Then, I use modules 'sale' and 'sale_layout' to create a quotation. I had created my own module, and i use <xpath> to modify the original 'sale' and 'sale_layout' to create my own quotation template. The problem is, when I download the quotation.pdf the 'sale_layout' function I use doesn't appear. SO i think it's a problem with the order of differents views, my own view is apply after the others so only it is visible.
I hope, you understood me, thanks for your help.