Why aren't all of my Dialog buttons themed/styled ?

Why aren't all of my Dialog buttons themed/styled ?

I'm also using the datepicker but the datepicker buttons ARE themed/styled.

I'm using Dialog in other areas of my web site - and those Dialogs DO have properly themed buttons.

Which styles apply to these buttons?

Do these buttons use images?

If so, where are the images "supposed" to go? Relative to the stylesheet?

Thanks,

(Using JQ UI 1.8.1 and JQ 1.4.2)