Custom style not applying to THEAD tag in IE

I am using DataTables 1.8.2 with jQuery 1.8.3.

I have added a CSS class to THEAD tage for formatting the table associated with the DataTables plugin.
$('thead').addClass("cssClassName");

I can see the applied style in Firefox(16.0.2) but not in IE8. Is there any alternate way to apply the style in both the browsers.

Thanks for any help!