The current beer corpus used by Brewery Master only contains a small number of documents. Due to its small size, its very likely the the answer Watson is searching for doesn't exist.
Totally see your point, but it makes me wonder why IBM point to this demo as an example of Watson API usage (and how good it is) when the demo doesn't live up to (anything like?) Watson's true potential.
Strikes me as a little counterproductive from a marketing POV.