hover image input submit button not working for ie 7 & 8

Question

I have the following simple form inside there is a button for submit , the CSS hover feature doesn't work for IE 7 or IE 8 , The first image is showing blank and when you hover on it , it shows the hover image , please help

HTML Button code

  <input type="submit" value="" class="btn submit-btn">

CSS for submit-btn

.submit-btn{
background: url("/images/up.png") no-repeat scroll 0 0 rgba(0, 0, 0, 0);
display: block;
font-size: 17px;
height: 34px;
margin: auto;
padding-left: 0;
padding-right: 0;
text-align: center;
width: 100px;
float:left;
color:#ffffff;
border:0 none;
 }
 .submit-btn:hover {
background: url("/images/down.png") no-repeat 0 0;
color:#ffffff;
}

Thanks in advance

Answer 1

Remove the RGBA attribute. It does not work in IE6 - 8.