Javascript issue in header.php

Hi

I am trying to have a floating div block. For that i Have done following:

In header.php (using jQuery):

$(document).ready(function()
{
$(window).scroll(function()
{
  $('#globalnav').animate({top:$(window).scrollTop()+"px" },{queue: false, duration: 350});
});

$('#close_message').click(function()
{
  //the messagebox gets scrool down with top property and gets hidden with zero opacity
  $('#globalnav').animate({ top:"+=15px",opacity:0 }, "slow");
});
});

Issue:
This works perfectly on the landing page of the blog but on the individual post page the same thing doesn’t work. It shows me the globalnav menu but it neither scrolls nor closes. Seems like problem with my javascript ($(document).ready(function() isnt called again probably in other page) but am not sure

Thanks