Dynamic Elements Not Picking Up Styles In IE7?

I'm writing some custom JavaScript that creates div elements on the fly, then creates class and ID attributes on the fly as well. For example, the div being created looks like this:

Code:
<div id="name_message" class="error_message">
In my stylesheet, I have declared this:

[Code]....

In Firefox 3, this works fine. When the element is created, the styles for "error_message" are applied. But in IE7, it does not pick up those styles. I can declare them via JavaScript, and that works fine, but I would rather not do that.

I can provide more specific code, if required, but this seems pretty straightforward. There are no errors or warnings in my JS code.

Does anyone know why IE7 (and IE6, for that matter) is not picking up the stylesheet declarations for this dynamic element? Is this something peculiar to IE's handling of styles on dynamic html elements?