Disappearing Button in Python Script after executing .net Addon

I have a small addon in .net which changes the author and description of a file. See attatchment.

To start the addon I took a python template from the tutorial. See files.
Once I start the application it seems that the addon is already executed the first time and after pressing the button to execute my TestCommand the button disappears and I don’t know why. What am I doing wrong?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.ComponentModel.Composition;
using Caliburn.Micro;
using VisualComponents.Create3D;
using VisualComponents.UX.Shared;

namespace TestPlugin
    //action or netCommand
public class MyTest : ActionItem
    //private Lazy<IApplication> app = null;
    public MyTest() : base("TestCommand")


    public override void Execute()
        IApplication app = IoC.Get<IApplication>();
        ISimWorld sim = app.World;
        sim.LayoutMetadata.Author = "TEST";
        sim.LayoutMetadata.Description = "Hello";
        IMessageService ms = IoC.Get<IMessageService>();
        ms.AppendMessage(sim.LayoutMetadata.Author, MessageLevel.Warning);

//plugin calling my action
public class MyPlugin : IPlugin
    void IPlugin.Exit()

    void IPlugin.Initialize()
        ICommandRegistry cr = IoC.Get<ICommandRegistry>();

Plugin.TestPlugin.dll (4.5 KB) Plugin.TestPlugin.pdb (19.5 KB)

init.py|attachment (1.4 KB) Hello PDV.py (357 Bytes) PyResource.German.xaml (1020 Bytes) ShowContextualRibbonTab.py (276 Bytes)

Have you tried to call executeInActionPanel() again after you execute the other command? That might reopen the panel again. I guess executing a command closes other commands…

Unfortunately that didn’t work. The Button is still gone after the first execution