当我订阅DolphinDB Java API时为什么会返回此错误消息

Question

我在dolphindb中有一张桌子：

t = streamTable(30000:0,`id`time`sym`qty`price[INT,TIME,SYMBOL,INT,DOUBLE])
share t as Trades

我想在Java客户端中预订此表。

PollingClient client = new PollingClient(8892);
TopicPoller poller1 = client.subscribe("localhost", 8848, "Trades");

但是它具有以下错误：