getting bad-request(400) while sending pubsub node

Hell all,

i am getting "bad-request(400)" error while send pubsub node here is my code

// Create a pubsub manager using an existing Connection

                PubSubManager mgr = new PubSubManager(connection);

                // Create the node

                ConfigureForm form = new ConfigureForm(FormType.submit);

                form.setAccessModel(AccessModel.open);

                form.setDeliverPayloads(true);

                form.setNotifyRetract(true);

                form.setPersistentItems(true);

                form.setPublishModel(PublishModel.open);

                LeafNode leaf =(LeafNode) mgr.createNode("abc_1", form);           

                leaf.send(new Item("123abc"));

here is my error log.

bad-request(400)

at org.jivesoftware.smackx.pubsub.packet.SyncPacketSend.getReply(SyncPacketSend.ja va:53)

at org.jivesoftware.smackx.pubsub.packet.SyncPacketSend.getReply(SyncPacketSend.ja va:61)

at org.jivesoftware.smackx.pubsub.LeafNode.send(LeafNode.java:299)

at org.jivesoftware.smackx.pubsub.LeafNode.send(LeafNode.java:276)