R shiny app is not reactive - r

Question

I have been working with the Shiny package, there is one function, which the user is able to select from a list of choices, based on the choice, the plot will update. however, right now the app does not update when the selection changes.
server.R
----------
library(shiny)
library(quantmod)
library(TTR)
shinyServer(function(input, output, session) {
selectedsymbol <- reactive({
symbol <- input$selectstock
})
output$stockplotoverview <- renderPlot({
symbolinput <- selectedsymbol()
getSymbols(symbolinput)
chartSeries(get(symbolinput))
addMACD()
addBBands()
})
output$candlechart <- renderPlot({
symbolinput <- input$selectstock
getSymbols(symbolinput)
candleChart(get(symbolinput),multi.col=TRUE,theme="white")
})
output$barchart <- renderPlot({
symbolinput <- input$selectstock
getSymbols(symbolinput)
barChart(get(symbolinput))
})
})
ui.R
library(shiny)
shinyUI(fluidPage(
# Application title
titlePanel("Hello Shiny!"),
# Sidebar component
sidebarLayout(
sidebarPanel(
selectInput("selectstockset", label = h3("Select the stock set"), choices = list("My Stock set" = 1,
"Good Stock Set" = 2,
"Customize" = 3), selected = 1),
selectInput("selectalgo", label = h3("Select the algorithm"), choices = list("Worst Increment" = 1,
"PAMR" = 2,
"SMA" = 3), selected = 1),
dateRangeInput("daterange", label = h3("Date Range")),
submitButton("Simulate")
),
# Show a plot of the generated distribution
mainPanel(
tabsetPanel(
tabPanel("Stock Set",
helpText("Select a stock to examine.
Information will be collected from yahoo finance."),
textInput("stocksetname", label = h4("Stock Set Name"),
value = "Enter text...") ,
# uiOutput("selectstock"),
selectInput("selectstock", label = h4("Select the stock"), choices = list("AAPL" = "AAPL",
"SBUX" = "SBUX",
"GS" = "GS")),
tabsetPanel(
tabPanel("Overview",
plotOutput("stockplotoverview")
),
tabPanel("Candle Chart",
plotOutput("candlechart")
),
tabPanel("Bar Chart",
plotOutput("barchart"))
),
hr(),
fluidRow(
column(3,
actionButton("addtostockset","Add to stock set"),
tags$style(type='text/css', "#addtostockset { align: right;}")
),
column(3,
actionButton("confirm","Confirm stock set"),
tags$style(type='text/css', "#confirm { align: right; }")
)
)),
tabPanel("Simulation Window"),
tabPanel("Statistical Result")
)
)
)))

Answer 1

Nothing is returned by your reactive conductor:
selectedsymbol <- reactive({
symbol <- input$selectstock
})
Use
selectedsymbol <- reactive({
symbol <- input$selectstock
return(symbol)
})