Revit API AddInCommandBinding for ID_PROCESS_DROP

我试图将一个家庭的拖放绑定到项目中并禁用它。

我的代码是基于Revit 2014 SDK样本禁用命令

我的代码有。canhavebinding测试，我有一个显示成功或失败的对话框。当我运行命令时，它显示成功，但我仍然可以拖放家庭。什么好主意吗?

RevitCommandId commandId2 = RevitCommandId.LookupCommandId("ID_PROCESS_DROP"); 
    if (!commandId2.CanHaveBinding)
    {
        TaskDialog.Show("Error", "Drag/Drop cannot be overridden.");
    }
    else
    {
        TaskDialog.Show("Success", "Drag/Drop can be overridden.");
    }
try
{
    AddInCommandBinding dropBinding = uiapp.CreateAddInCommandBinding(commandId2);
    dropBinding.Executed += new EventHandler<Autodesk.Revit.UI.Events.ExecutedEventArgs>(dragDropDisable);
}
catch (Exception ex)
{
     Console.WriteLine("Error: {0}",ex.ToString());
}
    private void dragDropDisable( object sender, Autodesk.Revit.UI.Events.ExecutedEventArgs args)
{
TaskDialog.Show("Disabled", "Never Drag/Drop families into your project!");
}

dropBinding.Executed += dragDropDisable;