Hi, I want to increase test categories div height 100% with background image. This panel is on left side. Here is the URL: The Euro Grads (Get Better Results)

HTML Code:

<div id="rightmenu">
<div id="menuheadback"><div class="menuhead">Test Categories</div></div>
<div id="manuelinks">
</div>
</div>
CSS Code:
#rightmenu
{
float:left;
width:240px;
}
#menuheadback
{
width:240px;
height:38px;
background-color:#000000;
}
.menuhead
{
color:#FFFFFF;
font-family:Verdana;
font-size:20px;
font-weight:bold;
padding-left:10px;
padding-top:5px;
}
#manuelinks
{
width:240px;
background-image:url(images/menubackground.jpg);
height:100%;

}
i try so many things but can't able to increase the height to 100%;.
Any one can help me plzz