Hopper forget Item

Build a row of 16 or more hoppers, putt redstonedust over the first 15 hoppers and let them powered from a comperatoron the end of the hopperrow.
If you putting Items in the first hopper, the items will flow on after other to the hopperend to the comperator.
The comperator powered the redstone over the hopper and 5th and the 13th hoppers seems to forget he item in it.