Error: path for html_dependency not provided R Markdown selectInput

I have a problem with my R Markdown project. I can not add a select input or even a sliderInput. When I click Build Website I get this error message: Error: path for html_dependency not provided Execution halted I watch many topics but I can not solve my problem.

Can you help me ? thank you in advance !

---
  title: "Untitled"
  author: "qc"
  date: "May 30, 2017"
  output: flexdashboard::flex_dashboard

---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = TRUE)
library(flexdashboard)
library(ggplot2)
library(shiny)
library(datasets)
```

Inputs {.sidebar}

```{r, echo=FALSE}

inputPanel(
radioButtons("category",label= "Select  Category",choices=c("diffPts","diffGF","diffGA","diffGD","diffpos"),inline = TRUE),

selectInput("dataset","Choose :", 
              choices = c("ezce","efzf","zef"))



```