flash聊天系统客户端的用户列表为什么无法显示？

var xstransferrer:xmlsocket = new xmlsocket（);
var scurrentscreen = "login";
initsocketconnection（xstransferrer);
showloginscreen（);
initializescreens（);

function showloginscreen（):void{
    ctimessage.visible = true;
    ctiusername.visible = true;
    cbtlogin.visible = true;
    ctachatdisplay.visible = false;
    ctainput.visible = false;
    cluserlist.visible = false;
    cbtsend.visible = false;
    cbtusers.visible = false;
    scurrentscreen = "login";
}
function showchatscreen（):void{
    ctimessage.visible = false;
    ctiusername.visible = false;
    cbtlogin.visible = false;
    ctachatdisplay.visible = true;
    ctainput.visible = true;
    cluserlist.visible = true;
    cbtsend.visible = true;
    cbtusers.visible = true;
    scurrentscreen = "chat";
}

function showconnectedmessage（bdidconnect:boolean):void{
    if（bdidconnect){
        ctimessage.text = "connected...please enter a username";
    }
    else{
        ctimessage.text = "connect error!";
    }
}

function showdisconnectedmessage（):void{
    showloginscreen（);
    ctimessage.text = "trying to reconnect...";
    ctiusername.text = "";
    xstransferrer.connect（"localhost",2001);
}

function initsocketconnection（xssocket:xmlsocket):void{
    xssocket.ondata = function（sdata:string):void{
        var xmldata:xml = new xml（);
        xmldata.ignorewhite = true;
        xmldata.parsexml（sdata);
        var imdata:incomingmessage = new incomingmessage（xmldata);
        
        switch（imdata.messagetype){
            case "signonsuccess":
                showchatscreen（);
                break;
            case "userlistupdate":
                cluserlist.dataprovider = imdata.users;
                break;
            case "chat":
                ctachatdisplay.text += imdata.fromuser + ":" + imdata.chattext + newline;
                ctachatdisplay.vposition = ctachatdisplay.maxvposition;
            default:
        }
    };
    
    xssocket.onconnect = function（bdidconnect:boolean):void{
        showconnectedmessage（bdidconnect);
    };

    xssocket.onclose = function（):void{
        showdisconnectedmessage（);
    };
    
    xssocket.connect（"localhost", 2001);
}

function initializescreens（):void{
    ctachatdisplay.html = true;
    cbtlogin.label = "log in";
    cbtsend.label = "send";
    
    var ologinlistener:object = new object（);
    ologinlistener.form = this;
    ologinlistener.socket = xstransferrer;
    ologinlistener.click = function（oevent:object):void{
        if（this.form.ctiusername.text != ""){
            var omlogin:outgoingmessage = new outgoingmessage（"login", this.form.ctiusername.text);
            this.socket.send（omlogin.message);
        }
    };
    
    ologinlistener.onkeydown = function（):void{
        if（key.getcode（) == key.enter && this.form.scurrentscreen == "login"){
            this.click（);
        }
    };
    cbtlogin.addeventlistener（"click", ologinlistener);
    key.addlistener（ologinlistener);
    
    var ochatlistener:object = new object（);
    ochatlistener.form = this;
    ochatlistener.socket = xstransferrer;
    ochatlistener.click = function（oevent:object):void{
        if（this.form.ctainput.text != ""){
            var omhat:outgoingmessage = new outgoingmessage（"chat", this.form.ctiusername.text, this.form.ctainput.text);
            this.socket.send（omhat.message);
            this.form.ctainput.text = "";
        }
    };
    
    ochatlistener.onkeydown = function（):void{
        if（key.getcode（) == key.enter &&
            this.form.scurrentscreen == "chat"){
            this.click（);
        }
    };
    cbtsend.addeventlistener（"click", ochatlistener);
    key.addlistener（ochatlistener);
/*    
    cbtusers.label = "refresh";
    var ouserlistener:object = new object（);
    ouserlistener.form = this;
    ouserlistener.socket = xstransferrer;
    ouserlistener.click = function（oevent:object):void{
        var imuser:incomingmessage = new incomingmessage（);
    };
    
    ouserlistener.onkeydown = function（):void{
        if（key.getcode（) == key.enter &&
            this.form.scurrentscreen == "chat"){
            this.click（);
        }
    };
    cbtusers.addeventlistener（"click", ouserlistener);
    key.addlistener（ouserlistener);*/
}