Valuebox is not shown in flexdashboard

My valuebox is not shown in the output, only text. Did I miss something?

---
title: "Untitled"
author: "June Tseng"
date: "1/12/2020"
runtime: shiny
output:
  flexdashboard::flex_dashboard:
  flexdashboard::valueBox():
  orientation: rows
  ource_code: embed
  vertical_layout: fill
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
library(flexdashboard)
```

## valueBox

```{r pressure}
renderValueBox({valueBox(42, caption = "Test", icon="fa-thumbs-down")})
```

There is something off with your yaml header. Does the reprex is not correct or do you have that in your code as well ?

In flexdahsboard, headers for parts should be with ### not just two. See the doc
https://rmarkdown.rstudio.com/flexdashboard/index.html#layout

You also need to add a special syntax for the layout as seen in the doc too
https://rmarkdown.rstudio.com/flexdashboard/using.html#layout-by-row

Try without shiny first. Your example does not require shiny here.

Then you'll be able to add some shiny reactivity following the doc
https://rmarkdown.rstudio.com/flexdashboard/shiny.html
and example with valueBox like the CRAN dashboard live and source

Hope it helps