shinydashboard中的menuSubItem

Question

我想在shinydashbaord的侧边栏中添加子菜单，但它没有显示， 我的问题出在哪里：

  shinyUI( 
  dashboardPage(skin = "blue",
    dashboardHeader(title = "Decison Support System"),
    dashboardSidebar(
      sidebarMenu(
      menuItem("Setting", tabName = "setting", icon = icon("cog")),
      menuItem("Dashboard", tabName = "dashboard", icon = icon("dashboard")),
      menuItem("Charts", tabName = "charts", icon = icon("bar-chart"),
            menuSubItem("subcharts", tabName = "subcharts",icon = icon("cog")
      )),
      menuItem("Raw Data", tabName = "rawdata", icon = icon("table")))
      ),
    dashboardBody(
  )

))