下载shapefile时遇到错误

Question

我正在尝试下载来自writeOGR函数的shapefile。但它无法正常工作，无法下载shapefile。有谁知道如何解决这一问题？我真的很感激！服务器来了.R：

  output$shapefile <- renderUI({

  if(is.null(input$action))
    return(NULL)
  else
    isolate({ 
    if(is.null(input$checkboxpd))
      return(NULL)
    else
      downloadHandler(
        filename = function() {
          paste("Arvores_indiv_LiDAR", "shp", sep=".")
        },
        content = function() { 

        trees5 <- FindTreesCHM(fchm(), (as.numeric(input$fws)), (as.numeric(input$minht)))
        lots <- SpatialPointsDataFrame(coords = cbind(trees5), data = trees5)
        writeOGR(lots, dsn="Arvores_indiv_LiDAR.shp", layer = "Arvores_indiv_LiDAR", driver = "ESRI Shapefile")
        dev.off

        })    
    })
    })

非常感谢！ ：）