背景图片更改：悬停在IE中无效（在6,7,9上测试）

Question

这是我的sass代码：

    .prev_next
      position: absolute
      z-index: 10
      width: 746px
      li
        list-style: none
        display: block
        width: 240px
        height: 490px
        position: absolute
        &.prev
          left: 0px
          a
            &:hover
              background-image: url("/images/prev.png")
        &.next
          right: 0px
          a 
            &:hover
              background-image: url("/images/next.png")
        a
          display: none
          width: 100%
          height: 100%
          cursor: pointer
          background:
            position: center
            repeat: no-repeat
        &.active
          a
            display: block     

HAML：

    #pn_navi
      %ul.prev_next
        %li#prev_id.prev
          %a{:href => "#", :title => "previous"}
            %span.arrow <
            %span.label previous
        %li#next_id.next.active
          %a{:href => "#", :title => "next"}
            %span.label next
            %span.arrow >
    %ul
      %li.active
        %img{:src => "/images/image_3.jpg"}
          .gallery_content
            %h1 Title
            %p Lorem Ipsum
      %li
        %img{:src => "/images/image_4.jpg"}
          .gallery_content
            %h1 Title 
            %p Lorem Ipsum