HTML Code:
 this.get_rooms_button = new DwtButton ({parent:this._parentView, name:"get_rooms_button", id:"get_rooms_button", listeners: new AjxListener(this.get_rooms_button,this.get_rooms_button_listener())});
            this.get_rooms_button.setText("get rooms");

com_zimbra_om.get_rooms_button_listener = function(){
    var url = ZmZimletBase.PROXY + AjxStringUtil.urlComponentEncode(com_zimbra_om._url);
    var request_url = 'http://demo.openmeetings.de/openmeetings/services/UserService/getRooms?SID=' +
                    sid ;
                        //HANDLE THE RETURNED VALUES
    AjxRpc.invoke(request_url, ["Content-Type", "application/soap+xml;charset=utf-8", "SOAPAction", "http://url/openmeetings/services/UserService/getSession"], new AjxCallback(this, this._reponseHandler, postCallback) , true);
    this._get_rooms_parentView = new DwtListView({parent:this.getShell(),noMaximize:false});
    this._get_rooms_parentView.setSize("200","200");
    this.get_rooms_dialog = this._createDialog({title:"Rooms", view:this._get_rooms_parentView, standardButtons : [DwtDialog.OK_BUTTON]});
    this.get_rooms_dialog.setButtonListener(DwtDialog.OK_BUTTON, new AjxListener(this, this._okBtnListner));
    this.get_rooms_dialog.popup();
};
I am getting the error that "this.get_rooms_button_listener() is not a function".
Where am I wrong?
Thanks.