Embedded Image isn't loading

I'm trying out embedded images. First I get constantly "MarkupExtension not found for local". This is fixed it seems. My image is still not loading.
What am I doing wrong?
Some noob questions:
What assembly should I reference on this line?
xmlns:image="clr-namespace:Images"
What is the path to my image? Is App4.scooter.png correct?

I'm so confused and frustrated by all the erros I saw the last couple days.

This is my code: imgur.com /a/3id7ntu

using System;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;

namespace Images{
    [ContentProperty(nameof(SourceID))]
    public class ImageResourceExtension : IMarkupExtension
{
    public string SourceID { get; set; }

    public object ProvideValue(IServiceProvider serviceProvider)
    {
        if (SourceID == null)
        {
            return null;
        }

        // Do your translation lookup here, using whatever method you require
        var imageSource = ImageSource.FromResource(SourceID);

        return imageSource;
    }
}
}

   <?xml version="1.0" encoding="utf-8" ?>
    <ContentPage xmlns="xamarin.com/schemas/2014/forms"
                 xmlns:x="schemas.microsoft.com/winfx/2009/xaml"
                 xmlns:local="clr-namespace:App4"
                 xmlns:image="clr-namespace:Images"
                 x:Class="App4.MainPage">

        <StackLayout>
            <!-- Place new controls here -->
            <Image Source="{image:ImageResource App4.scooter.png}" />


        </StackLayout>

    </ContentPage>