lemonade & compass 0.10 conversion

gistfile1.css

this is what I want:
background: sprite-image('gradients/footer.png', 0, 0, 50px, 50px) transparent repeat-x;

this is what I tried:
$gradients-repeat: repeat-x;
$gradients-spacing: 50px;
@import 'gradients/*.png';

@include gradients-sprite(footer);

which outputs:
.gradients-sprite {
  background: url('/images/gradients-sa9d5ed73f1.png') no-repeat;
}