Authentication Required Error for the below Request

Hi Team,

Got the below Error 

Action.c(220): Error -26547: Authentication required, please use web_set_user, e.g. web_set_user("domain\\user", "password", "host:port");   [MsgId: MERR-26547]

Could anyone please help me out for the below request.

web_custom_request("24.0", 
        "URL={p_URL}", 
        "Method=POST", 
        "Resource=0", 
        "RecContentType=application/json", 
        "Referer={p_URL1}", 
        "Snapshot=t27.inf", 
        "Mode=HTML", 
        "EncType=application/json;charset=UTF-8", 
        "Body=[{\"version\":\"1.0\",\"minimumVersion\":\"0.9\",\"channel\":\"/meta/handshake\",\"supportedConnectionTypes\":[\"long-polling\",\"callback-polling\"],\"advice\":{\"timeout\":60000,\"interval\":0},\"id\":\"1\"}]", 
        LAST);

Got some Idea regarding the above request: 
http://docs.genesys.com/Documentation/GMS/latest/API/ChatAPI