Current Page Link Not Working

here is my code:

.menu ul {list-style:none; margin:0 0 0 12px; padding:0px; width:890px; height:40px;}
.menu ul li {display:inline-block; float:left; padding:0px; margin:0px; text-align:center; }
.menu ul li a {display:inline-block; width:175px; color:#E6F7CB; font-size:15px; background:url('images/bg-menu.png') top; text-decoration:none; margin:0px; padding:10px 0px 10px; height:20px; position:relative; z-index:39 }
.menu ul li a:hover,
.menu ul li.current_page_item a {color:black; background:url('images/bg-menu-hover.png') top; position:relative; z-index:41;}
.menu ul li:hover {color:black}

the hover works fine, but the current will just not work.

Any thoughts?