图像边框firefox只填充角落

Question

当我使用边框图像属性时，会出现四个方块，每个角落一个，但两侧没有任何东西。我做错了什么？

height:400px;
width:200px;
border-style:solid;
border-width:60px;
 border-left-width:60px;
border-image:url("images/red2.png") 20 20 20 20 stretch;
-webkit-border-image:url("images/grid.png") 20 20 20 20 stretch;
-moz-border-image:url("images/pattern.png") 20 20 20 20 repeat;
-ms-border-image:url("images/grid.png") 20 20 20 20 repeat;
-o-border-image:url("images/red2.png") 20 20 20 20 repeat;
position:fixed;