IE下bug

#G-lightbox-popup .lightbox-pic-view .lightbox-btn{

width: 40%;

height: 100%;

    position: absolute;

    top: 0;

    z-index: 1;

    background: url("../images/transparent.png") repeat left top;

}

加了    background: url("../images/transparent.png") repeat left top;之后左右切换的按钮在IE下还是出不来……求助~