CSS Pop-Up Image Code Not Working

Please check this page. You’ll see that the hover/pop-image image function works for the thumbnail images but it should also work for the main/largest product image on the page. The css hover/pop-up code for the large product image works okay in all browsers except Chrome and Safari. I’ve looked through the code a bunch of times. Why isn’t the code working for the largest prod. image in Chrome and Safari?

The pop-up for the largest product image does not work in my Chrome (v. 6.0.472.63) and Safari (v. 5.0.2) browsers.

do this :
.prodpageimglrg:hover {

background-color: transparent;
z-index: 999;