i would like to put my own my backgroudnd image behind a calendar but it´s impossible. how can i do that.

MY code:
<div id="calendario">
<!-- html code for the module to show a calendar-->
</div>

CSS style:

#calendario { color: #FFFFFF; padding:5px 70px 0px 20px; font-family:Garamond;height:120px; width:260px; background: url(../images/bg-cumple.jpg) no-repeat }