a:hover doesn't work on firefox, but with IE8

Hi Guyes,

I hope you can help me here. I just can't figure out why the hover function doesn't work in firefox, but with IE.

Here is the code:

#albumwrapper
{
 width:99%;
 height:520px;
 padding:0px;
 margin:0px;
 overflow:auto;
 margin-top:10px;
 margin-right:10px;
 border:2px solid;
}

#albumbox
{
 width:145px;
 height:130px;
 margin:20px;
 float:left;
}

#albumbox a:hover
{
 background-color:black;
}

Code (markup):

 echo "<div id='albumbox'>";
            echo "<a href='albums/picturedisplay.php?album=$album_query&site=album'>";
            echo "<img src='$thumbnail_query/$pic_query' name='$pic_query' width=140px height=100px/>";
            echo "</a>";
            echo "<p align='center'>"."$album_query"."</p>";
            echo "</div>";

HTML:

 

Your link image covers the background color, I guess.