Using 2 Word Blocks With Fill Command

Mojang.
This May not be a bug just a misunderstanding. When I try to use the fill command ! type in the coordinates and then I type in the name of the block. In 14w11b, I realized numerical ids no longer are eligible. But When I Try to type in a 2 word block (ex. black wool) It Wont work. I tried everything from black_wool, wool:15, wool:black, wool/15, wool/black and <Black Wool>. Nothing Seems To Work. Please Let me know if this is a bug or it is my fault.