Damage tag not working in /testfor

I was creating a map, when I encountered a problem in testing for dropped items with damage values. It looks like the Damage tag doesn't work in /testfor. I dropped a sand item, then used /testfor @e[type=Item] {Item:{id:minecraft:sand,Damage:0s,Count:1}}. Minecraft responded with, "item.tile.sand.default did not match the required data structure". I tried the same thing with red sand. I used, "/testfor @e[type=Item] {Item:{id:minecraft:sand,Damage:1s,Count:1}}" This time minecraft said, "item.tile.sand.red did not match the required data structure" I am pretty sure this is a bug. I tested everything multiple times.