Problems with custom attributes on data members / properties

I created a custom attribute class below:

    public class MyCustomAttribute : System.Attribute
    {
        public string Description 
        { 
            get {return _description;} 
            set {_description = value;}
        }

        string _description =   string.Empty;

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="description">The description of the property ie: "User Name"</param>
        public MyCustomAttribute(string description)
        {
            _description = description;
        }
    }

I then applied that to a simple property:

public class MyDataClass
{
     [MyCustomAttribute("UserAge")]
     public int UserAge;
}

However when I try to get the list of attributes on the data member, the MyCustomAttribute doesn't show up

       public main()
       {
            MyDataClass myDataClass = new MyDataClass();
            Attribute[] attrs = Attribute.GetCustomAttributes(myDataClass.UserAge.GetType());

            foreach (Attribute attr in attrs)
            {
                if (attr is MyCustomAttribute)
                {
                    SubComponent sc = attr as MyCustomAttribute;
                    System.Diagnostics.Debug.WriteLine("UserAge" + sc.Description);

                }
            }
        }

It works GREAT on classes, but for properties it just doesn't seem to hold.