Partial Declaration must not specify different Base Classes

I repeatedly get this Error Message:Partial Declaration must not specify different Base Classes. Can somebody tell me what may be the cause of this. Here's my code.

CashAdvancePage.xaml

    <?xml version="1.0" encoding="utf-8" ?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             x:Class="ebmsMobile.CashAdvancePage"
             Title="Cash Advance"
             BackgroundImage="bg3.jpg">
  <Label Text="This is the Cash Advance Page." VerticalOptions="Center" HorizontalOptions="Center" />
</ContentPage>

CashAdvancePage.xaml.cs

 using System;
    using System.Collections.Generic;
    using System.Linq;
    using System.Text;
    using System.Threading.Tasks;

using Xamarin.Forms;

namespace ebmsMobile
{
    public partial class CashAdvancePage : ViewCell
    {
        public CashAdvancePage()
        {
            //InitializeComponent();
            //NavigationPage.SetHasNavigationBar(this, false);

            var image = new Image
            {
                HorizontalOptions = LayoutOptions.Start
            };
            image.SetBinding(Image.SourceProperty, new Binding("ImageUri"));
            image.WidthRequest = image.HeightRequest = 40;

            var nameLayout = CreateNameLayout();
            var viewLayout = new StackLayout()
            {
                Orientation = StackOrientation.Horizontal,
                Children = { image, nameLayout }
            };
            View = viewLayout;


        }

        static StackLayout CreateNameLayout()
    {
        var nameLabel = new Label
        {
            HorizontalOptions= LayoutOptions.FillAndExpand
        };
        nameLabel.SetBinding(Label.TextProperty, "DisplayName");

        var twitterLabel = new Label
        {
           HorizontalOptions = LayoutOptions.FillAndExpand,
           Font = Fonts.Twitter
        };
        twitterLabel.SetBinding(Label.TextProperty, "Twitter");

        var nameLayout = new StackLayout()
        {
           HorizontalOptions = LayoutOptions.StartAndExpand,
           Orientation = StackOrientation.Vertical,
           Children = { nameLabel, twitterLabel }
        };
        return nameLayout;
    }
    }
}

You need to inherit from ContentPage in the .cs when you use it as Rootelement in the XAML file.

The other problem is, that you need to assign your "viewLayout" to Content instead of View.

using Xamarin.Forms;

namespace ebmsMobile
{
public partial class CashAdvancePage : ContentPage // derive from ContentPage
{
    public CashAdvancePage()
    {
        //InitializeComponent();
        //NavigationPage.SetHasNavigationBar(this, false);

        var image = new Image
        {
            HorizontalOptions = LayoutOptions.Start
        };
        image.SetBinding(Image.SourceProperty, new Binding("ImageUri"));
        image.WidthRequest = image.HeightRequest = 40;

        var nameLayout = CreateNameLayout();
        var viewLayout = new StackLayout()
        {
            Orientation = StackOrientation.Horizontal,
            Children = { image, nameLayout }
        };
        Content = viewLayout; // <-- Set the ViewLayout as Content


    }

    static StackLayout CreateNameLayout()
    {
        var nameLabel = new Label
        {
            HorizontalOptions = LayoutOptions.FillAndExpand
        };
        nameLabel.SetBinding(Label.TextProperty, "DisplayName");

        var twitterLabel = new Label
        {
            HorizontalOptions = LayoutOptions.FillAndExpand,
       //     Font = Fonts.Twitter
        };
        twitterLabel.SetBinding(Label.TextProperty, "Twitter");

        var nameLayout = new StackLayout()
        {
            HorizontalOptions = LayoutOptions.StartAndExpand,
            Orientation = StackOrientation.Vertical,
            Children = { nameLabel, twitterLabel }
        };
        return nameLayout;
    }
}
}