JQuery :: Cookie Reading Not Working?

I create a cookie which contains a font size. My page content increases or decreases in size on each click event of the links that trigger a function. I have round this value up so it is always an integer value and store it inside a cookie called 'fontSize'.

I am using the following code to set the font size of the page that is loaded to be set at the value of the cookie but it never works, my page font size always reverts back to the standard font size set in my style sheet.

I am using the same code below to change the background colour of the web page and this works fine!

if(readCookie('fontSize')) {
$('body').css('font-size', readCookie('fontSize'));
}