background fixed to bottom

i want a picture to be displayed as a banner at the bottom of a box(div) so i figured i'd use background as to not be disturbed by the boxes margin settings and other div's inside of it

so i'm using this css but the image doesn't even display
#main_content {
  margin 0 auto;
  width:100%
  background:#fff url('images/banner.png') no-repeat fixed bottom;
  padding:15px 2px 10px 2px;
  border:solid 1px #121212;
}
it just doesn't get displayed. i can show it with a simple img tag so there is nothing wrong with the permissions or anything. i've even tried a gif thinking back on that MSIE problem even though i have no other browsers than safari, opera and firefox on my system

this is really bugging me and i know it's some weird thing in css that is over my head still so i hope you can help