Error: incorrect number of dimension Shiny

I am new to Shiny.

When I run the following code I get the message "incorrect number of dimension".

I would like to place a checkboxgroupinput next to every rows of NameGen table, which is a result of a selectInput. Then, if one row is checked, this will go in a new table in the mainPanel.

ui.r

library(shiny)

fluidPage(
  sidebarLayout(
    sidebarPanel(
      selectInput("select","Type",c("C","R","V"),selected=NULL),
      uiOutput("choose_row")
    ),
    mainPanel(
      tableOutput("result")
    )
  )
)

server.r

library(shiny)

function(input,output){
  data1<-reactive({
    setwd("/Users/me/Desktop/DirectoryAlR")
    AlData<-read.delim2("AlR.csv",sep=";",stringsAsFactors = FALSE)
    NameGen<-NULL
    for(i in 1:nrow(AlData)){
      if(AlData[i,7]==input$select){
        NameGen[i]<-AlData[i,1]
      }else{
        NameGen[i]<-NA
      }
    }
    NameGen<-NameGen[!is.na(NameGen)]
    return(NameGen)
    })

  output$choose_row<-renderUI({
    rn<-rownames(data1())
    checkboxGroupInput("box","",rn,selected=NULL)
  })


  result<-reactive({
    data2<-data1()
    data2[input$box,,drop=FALSE]
  })


  output$result<-renderTable(result())
}