Chat on frappe version-12 is not refresh

I setup frappe 12.5.1 on ubuntu. I open a chat direct to friend. I type a message and enter. I can not see my message on conversation history. My friend sent a message to me but the message don’t appear on conversation too. I have to close chat and reopen again. I investigate a chat and found that REST API ‘send’ was publish a message to the room successfully. but the message is not show in a windows.

Best Regard
Surachai Locharoen