Shiny: leaflet map is not working with rCharts

Question

Using this dat data.frame

set.seed(123)
stationID <- c(rep("station1", 3), rep("station2", 3), rep("station3", 3),rep("station4", 3))
x <-   c(rep(-77.2803, 3), rep(-79.1243, 3), rep(-93.4991, 3),rep(-117.632, 3))
y <-   c(rep(35.8827, 3), rep(42.4356, 3), rep(30.0865, 3),rep(34.0905, 3))
parameter <-  rep(c("A", "B", "C"), 4)
value <- c(sample(1200:1800, 3), sample(900:1300, 3), sample(1400:2200, 3), sample(850:1400, 3))
dat <- data.frame(stationID, x, y, parameter, value)
head(dat)

I created multi bar chart using rCharts as below

library(rCharts)
n1 <- nPlot(value ~ stationID, 
            group = "parameter", 
            data = dat, 
            type = "multiBarChart") 
n1$xAxis(axisLabel = 'Station')
n1$yAxis(axisLabel = 'Value')
n1$chart(margin=list(left=100,bottom=100))
n1$params$width <- 1700
n1$params$height <- 700
n1

Here's is the result

And I created leaflet map as below

library(tidyr)
dat1 <- tidyr::spread(dat, parameter, value)
library(leaflet)
leaflet(dat1) %>% 
  addProviderTiles("OpenStreetMap", group = "OpenStreetMap") %>% 
  addCircleMarkers(~x, ~y, radius= ~A/50, color ="red",
                   stroke = FALSE, 
                   fillOpacity = 0.4, 
                   group = "A", popup = ~as.character(A)) %>%
  addCircleMarkers(~x, ~y, radius= ~B/100, color ="green",
                   stroke = FALSE, 
                   fillOpacity = 0.4, 
                   group = "B", popup = ~as.character(B)) %>%
  addCircleMarkers(~x, ~y, radius= ~C/150, color ="blue",
                   stroke = FALSE, 
                   fillOpacity = 0.4, 
                   group = "C", popup = ~as.character(C)) %>%
    addLayersControl(position = "bottomleft",
                   baseGroups = c("OpenStreetMap"),
                   overlayGroups = c("A","B","C"))

Here's the result

I combined both of them in shiny app

library(shiny)
library(rCharts)
library(leaflet)
ui <- fluidPage(sidebarLayout(
  sidebarPanel(h1("Shiny app"), 
               tags$hr(),
               h2("several options here"), width =2),
  mainPanel(width = 10,
            uiOutput("tb"))))

server <- function(input,output){

  output$chart1 <- renderChart({
    n1 <- nPlot(value ~ stationID, 
                group = "parameter", 
                data = dat, 
                type = "multiBarChart") 
    n1$xAxis(axisLabel = 'Station')
    n1$yAxis(axisLabel = 'Value')
    n1$chart(margin=list(left=100,bottom=100))
    n1$addParams(dom="chart1")
    n1$params$width <- 1700
    n1$params$height <- 700
    return(n1) 
  })

  output$map1 <- renderLeaflet({

    leaflet(dat1) %>% 
      addProviderTiles("OpenStreetMap", group = "OpenStreetMap") %>% 
      addCircleMarkers(~x, ~y, radius= ~A/50, color ="red",
                       stroke = FALSE, 
                       fillOpacity = 0.4, 
                       group = "A", popup = ~as.character(A)) %>%
      addCircleMarkers(~x, ~y, radius= ~B/100, color ="green",
                       stroke = FALSE, 
                       fillOpacity = 0.4, 
                       group = "B", popup = ~as.character(B)) %>%
      addCircleMarkers(~x, ~y, radius= ~C/150, color ="blue",
                       stroke = FALSE, 
                       fillOpacity = 0.4, 
                       group = "C", popup = ~as.character(C)) %>%
      addLayersControl(position = "bottomleft",
                       baseGroups = c("OpenStreetMap"),
                       overlayGroups = c("A","B","C"))
  })


  output$tb <- renderUI({
    tabsetPanel(tabPanel("First plot", tags$br(), tags$br(), tags$br(),
                         showOutput("chart1", lib ="nvd3"),
                         tags$br(), tags$br(), tags$br(),
                         leafletOutput("map1", height = 750)))
  })
}
shinyApp(ui = ui, server = server)

rCharts plot worked fine but there was no data on the leaflet map.

Any suggestion would be appreciated?