Why don't you work inlude in jade?

Question

Node.js

Where do I connect:

extends layout
include nav.jade
block content
  h1= title
  p Welcome to #{title}
  form(action='/',method='post' )
    input(type='text')
    input(type='submit')

What I connect:

// Jade
ul
    li 
      a(href="/old")|old
    li  
      a(href="/new")|new
    li  
      a(href='/')|hom

index and nav are in the same folder, but the output is nothing.