Beamer presentation using R Markdown

Question

I'm using R Markdown to make a beamer presentation and I have an issue with slide level.

I choose the Frankfurt theme. This theme allows to have a presentation's plan (bullets in header).

My issue :
When I put "slide_level: 2", I have the content but not the presentation's plan.
When I put "slide_level: 3", I have the presentation's plan but content disappears.

What am I doing wrong ?

Hereunder is the R Markdown

---
title: "Herding"  
author:   
  - Loana  
institute:   
  - Supervised by   
  - University  
date: Academic year 2017-2018  
output:   
  beamer_presentation:  
    incremental: false  
    theme: "Frankfurt"  
    colortheme: "beaver"  
    fonttheme: "structuresmallcapsserif"  
    toc: true   
    slide_level: 2  
    fig_width: 5  
    fig_height: 4  
    fig_caption: true  
    highlight: tango  
link-citations: yes  
urlcolor: red  
linkcolor: red  
citecolor: blue  
---

----

# Title1

## Subtitle1

Text

----

# Title2

## Subtitle2

- Text
- Text

----

Answer 1

To get your desired result, set slide_level: 3 and, correspondingly, use ### to denote frame titles, e.g. ### Slide 1-1. It appears that # represents sections and ## subsections. If you do not wish to have subsections, create dummy subsections (see examples below) and set \AtBeginSubsection{} in your YAML header to suppress subsection title frames.

---
title: "Herding"  
author:   
  - Loana  
institute:   
  - Supervised by   
  - University  
date: Academic year 2017-2018  
output:   
  beamer_presentation:  
    incremental: false  
    theme: "Frankfurt"  
    colortheme: "beaver"  
    toc: true   
    slide_level: 3
    keep_tex: true
header-includes: 
- \AtBeginSubsection{}    
---

# Section 1
##

### Slide 1-1

- Text

### Slide 1-2

- Text

# Section 2
##

### Slide 2-1

- Text
- Text

### Slide 2-2

- Test

would give you