Dear All, I am trying to run simple code: *UI.R* library(shiny) shinyUI(fluidPage( titlePanel("Old Faithful Geyser Data"), sidebarLayout( sidebarPanel( selectInput("gb","gb",names(data)) , selectInput("var","var",names(data)) ), # Show a plot of the generated distribution mainPanel( plotOutput("distPlot") ) ) )) *SERVER.R * library(shiny) library(ggplot2) library(dplyr) library(testthat) load("/home/void/PISA/data.rda") shinyServer(function(input, output) { output$distPlot <- renderPlot({ df1<-group_by(data,input$gb) df2<-summarise(df1,ov=mean(input$var,na.rm=T)) hist(df2[,"ov"]) }) }) but I've received an error: Listening on http://127.0.0.1:6721 Warning in mean.default("CNT", na.rm = T) : argument is not numeric or logical: returning NA Error in hist.default(df2[, "ov"]) : invalid number of 'breaks' Warning in mean.default("PV4MATH", na.rm = T) : argument is not numeric or logical: returning NA Error in hist.default(df2[, "ov"]) : invalid number of 'breaks' I've checked that input$gb and input$var returns "CNT"... but dplyr expects CNT... Do you have any idea how to deal with this problem? Thanks, D [[alternative HTML version deleted]]