Why does on change only fire once?

Question

JavaScript

if res.code is '300'
    $( "#main" ).load "profile.html"
else
    $( "#main" ).load "signin.html"

Buttons with identifiers signingo and signoutgo are in different upload files.

$( document ).on "change", ".signin", () ->
    console.log 'in'

$( document ).on "change", ".profile", () ->
    console.log 'out'

The first time everything is fine, the second time it doesn't work...