 				return callback(new Error("tried to release timed out lock"))
 			else
 				profile.log("unlockScript:ok").end()
-				callback(err,result)
+				callback(null,result)

						return callback(err) if err? # error freeing lock
						callback null, false # tell caller they didn't get the lock
				else
					callback err, true, lockValue
			else
				metrics.inc "doc-blocking"
				profile.log("doc is locked").end()
				callback err, false

	getLock: (doc_id, callback = (error, lockValue) ->) ->
		startTime = Date.now()

			exists = parseInt exists
			if exists == 1
				metrics.inc "doc-blocking"
				callback null, false
			else
				metrics.inc "doc-not-blocking"
				callback null, true

	releaseLock: (doc_id, lockValue, callback)->
		key = keys.blockingKey(doc_id:doc_id)
