请问下为什么我获取群聊列表获取不了呢

[boyssimple]

NSXMLElement query = [NSXMLElement elementWithName:@"query" xmlns:@"http://jabber.org/protocol/disco#items"];
//conference 原生的
XMPPJID proxyCandidateJID = [XMPPJID jidWithString:[NSString stringWithFormat:@"%@.%@",GROUND,XMPP_HOST]];

XMPPIQ *iq = [XMPPIQ iqWithType:@"get" to:proxyCandidateJID  elementID:@"disco" child:query];
[self.xmppStream sendElement:iq];

执行之后不能走- (BOOL)xmppStream:(XMPPStream *)sender didReceiveIQ:(XMPPIQ *)iq 方法