jQuery not recognizing div id

Answer 1

Do you have that script after the html has loaded?

If not, put it inside this tag

$(document).ready(function() {
   // put all your jQuery goodness in here.
 });

The script could probably be executing before the HTML has loaded, hence the error.

Answer 2

The $('hello') selector matches on an element with a name of hello, $('#hello') would match on an element with an id of hello. Could you have mistakenly named the element instead of applying the id?

Answer 3

Could it be that you (or some component) is adding the Prototype library to your page? In Prototype, you select by ID using $('id') rather than $('#id'). Also, Prototype's $() function will return null if it doesn't find a match, while jQuery's $() function will never return null.

If Prototype (or another library with a $() function) is being loaded after jQuery, it would stomp all over jQuery's version of the $() function.

If it turns out this is the case, and you can't avoid using both jQuery and the other library, you'll probably want to take advantage of jQuery.noConflict.