I apologize for opening another thread on this, but I am trying to center my logo in the Header area. I have tried everything that was recommended in the closed thread [SOLVED] How to center the logo image? and nothing there has worked for me. Maybe it is operator error, in which case I still need some assistance.

I am working in WordPress 3.0 with Atahualpa 3.5.1. My logo is 509px wide by 230px high. I have configured my layout width to be fluid at 50%, my minimum width is 750px, and my maximum is 1250px. My browser is FF 3.6.6.
I have also tried centering the logo by the brute-force method of setting the margins in the Logo Image:Styling area, and none of them seem to have any affect on the logo placement. My logo remains left justified.

Can someone help me out?
Thanks in advance for your patience and assistance.
Nancy Graziano