创建Controller的问题：它说我的班没有钥匙，但是有

Question

错误：EntityType'Lead'没有定义键。定义此EntityType的键。 CLASS：EntityType：EntitySet'Leads'基于未定义键的'Lead'类型。

我的Web.config：

 <connectionStrings>
    <add name="DefaultConnection" connectionString="Data Source=localhost\MAC;AttachDbFilename=|DataDirectory|\macpartner.mdf;Initial Catalog=macpartner;Integrated Security=True"
      providerName="System.Data.SqlClient" />
    <add name="macpartnerContext" connectionString="Data Source=(localdb)\MSSQLLocalDB; Initial Catalog=macpartnerContext-20180927102419; Integrated Security=True; MultipleActiveResultSets=True; AttachDbFilename=|DataDirectory|macpartnerContext-20180927102419.mdf"
      providerName="System.Data.SqlClient" />
  </connectionStrings>

我的模型班：

using System.ComponentModel.DataAnnotations;

namespace macpartner.Models
{
    public class Lead
    {
        [Key]
        private int ID { get; set; }

        [Display(Name = "Nome")]
        private string nome { get; set; }

    }
}

我做错了什么？