I am working on livechat module and the error i am facing is that when the operator of the livechat is offline the visitor sends the message in the livechat but it is not appearing in the chatter like it do it when a real time chat is in progress 
the flow is that there are sellers and the customer may want to chat with diff sellers but the seller maybe online or offline so either the seller is offline or online the customer should be able to send message in the chat(which he can) and it should appear in the chat even when the seller is offline