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

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

			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)
