Why is my simple data binding not working? - xaml

Question

For the life of me I can't understand why this simple data binding isn't working at all.
First I tried it with the combo box (picker) items, and even though the string list "categories_names" gets populated with values in the code behind, they don't show up in the view.
Then I tried a simple text on a label, which didn't work either.
The XAML file:
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="budget.Pages.CreateItemBase"
BindingContext="budget.Pages.CreateItemBase">
<ContentPage.Content>
<StackLayout>
<Label
Text="{Binding Thing}"
VerticalOptions="CenterAndExpand"
HorizontalOptions="CenterAndExpand"
/>
<Picker
x:Name ="IB_Category"
ItemsSource="{Binding categories_names}"
Title="Select a Category"
VerticalOptions="CenterAndExpand"
HorizontalOptions="CenterAndExpand"
/>
</StackLayout>
</ContentPage.Content>
</ContentPage>
The code behind:
public partial class CreateItemBase : ContentPage
{
private List<Category> Categories;
private string thing;
public string Thing
{
get { return thing; }
set { thing = value; }
}
public IList<string> categories_names
{
get { return Categories.Select(x => x.Name).ToList(); }
set { Categories = new List<Category>(); }
}
public CreateItemBase ()
{
InitializeComponent ();
var z = BindingContext; // To check if the BindingContext is right during debug
Thing = "whatever";
SQLiteConnection DBCon = new SQLiteConnection(App.DBLocation);
DBCon.CreateTable<Category>(); // Creates the table if it doesn't exist yet
Categories = DBCon.Table<Category>().ToList();
DBCon.Close();
}
}
Any idea on what might be wrong? Much appreciated.