libGDX TileMapRenderer not doing anything

libGDX TileMapRenderer not doing anything

I was using this tutorial and tried to make the TileMapRenderer work, but I can't. It never renders anything, no matter what i do.
src:
public class GameScreen implements Screen {
TestGame game;
TiledMap map;
TileAtlas atlas;
TileMapRenderer tmr;
OrthographicCamera cam;

public GameScreen(TestGame game){
    this.game = game;

    map = TiledLoader.createMap(Gdx.files.internal("maps/level1.tmx"));
    atlas = new TileAtlas(map, Gdx.files.internal("maps/"));
    tmr = new TileMapRenderer(map, atlas, 5, 5);
    cam = new OrthographicCamera(800,600);
}

@Override
public void render(float delta) {
    Gdx.gl.glClearColor(0,0,0, 1);
    Gdx.gl.glClear(GL10.GL_COLOR_BUFFER_BIT);

    if(Gdx.input.isKeyPressed(Keys.LEFT)){
        cam.position.x=cam.position.x-Gdx.graphics.getDeltaTime()*300;
    }
    if(Gdx.input.isKeyPressed(Keys.RIGHT)){
        cam.position.x=cam.position.x+Gdx.graphics.getDeltaTime()*300;
    }
    if(Gdx.input.isKeyPressed(Keys.DOWN)){
        cam.position.y=cam.position.y-Gdx.graphics.getDeltaTime()*300;
    }
    if(Gdx.input.isKeyPressed(Keys.UP)){
        cam.position.y=cam.position.y+Gdx.graphics.getDeltaTime()*300;
    }
    if(Gdx.input.isKeyPressed(Keys.PLUS)){
        cam.zoom-=Gdx.graphics.getDeltaTime();
    }
    if(Gdx.input.isKeyPressed(Keys.MINUS)){
        cam.zoom+=Gdx.graphics.getDeltaTime();
    }      
    cam.update();

        // render map
    tmr.render(cam);   
    System.out.println("rendering");
}