How to create dependency property in WPF via XAML markup?

Question

WPF

Good afternoon! I'm learning WPF and I ran into this problem: I can't create a sample class through xaml markup that would contain a dependency property. Writes that there is no such class in the given namespace. . Although this class is in the solution explorer, tell me what could be wrong? How can it be corrected?
Class1 code:

using System;
using System.Windows;

namespace WpfDependency
{
    class Class1 : FrameworkElement
    {
        public static DependencyProperty DataProperty1;
        static Class1()
        {
            
            DataProperty1 = DependencyProperty.Register("Dataa", typeof(int), typeof(Class1));
        }
        public int Dataa
        {
            get
            {
                return (int)GetValue(DataProperty1);
            }
            set
            {
                SetValue(DataProperty1, value);
            }
        }
    }
}

Answer 1

Did you build the project after you created the class?