悬停图像主菜单

Question

这是当我悬停标题时，你可以看到有一点白色箭头，但当我翻看副标题时图像消失了。

#menu {
    float: left;
    height: 58px;
    width: 100%;
    margin-top: 30px;
}
#menu .menu_layer {
    float: left;
    height: 58px;
    width: 100%;
    filter: alpha(opacity = 50);
    -moz-opacity: 0.5;
    opacity: 0.5;
    border-top: #D8D6D2 1px solid;
    border-bottom: #F5F3F0 1px solid;
    background: #ffffff;
    z-index: 99;
}
#menu .menu_list {
    position: absolute;
    width: 100%;
    height: auto;
    z-index: 9999;
}
#menu .menu_list .egNav_menu_box {
    width: 940px;
    height: 60px;
    margin: 0 auto;
}
#menu .egNav_menu_box .egMenuLevel_0 {
    float: left;
    position: relative;
    display: block;
    z-index: 99999;
}
#menu .egNav_menu_box .egMenuLevel_0 a {
    display: block;
    line-height: 60px;
    font-size: 14px;
    float: left;
    margin-left: 48px;
    font-family: "open_sanslight";
    font-size: 16px;
    color: #666666;
}
#menu .egNav_menu_box .egMenuLevel_0:first-child a {
    margin-left: 0px;
}
#menu .egNav_menu_box .egMenuLevel_0 a:hover {
    color: #4E2581;
    background: url("/resources/images/bg_menu_hover2.png") no-repeat center bottom;
}
#menu .egNav_menu_box .egSelected.egMenuLevel_0 a {
    color: #4E2582;
    background: url("/resources/images/bg_menu_hover.png") no-repeat center bottom;
}
#menu .egNav_menu_box .egSelected.egMenuLevel_0 .egMenuLevel_1 a {
    color: #666666;
    background-image: none;
}
#menu .egNav_menu_box .egSelected.egMenuLevel_0 .egMenuLevel_1 a:hover {
    color: #4E2581;
}
#menu .egNav_menu_box .egMenuLevel_0 a.sub_menu_link:hover {
    color: #4E2581;
}