Hoppers don't input items to powered dispensers

What I expected to happen was:
When I place items in a hopper above a powered dispenser the items should go into the dispenser

What actually happened was:
The items in the hopper stayed there, without the hopper being powered

Steps to reproduce:
1.- Place a redstone torch (or any block that outputs a redstone signal) 2 blocks next to a dispenser
2.- Connect the torch to the dispenser using redtone dust
3.- Place a hopper above the dispenser
4.- Place some items inside the hopper
5.- The items will stay in the hopper and won't be moved to the dispenser