C# - COM – Can not change Level.Name

I would like to change the name of a level, but it don't work.

I use the „Text.dgn“ Example for testing.

Here is a part of the code.

I use: bentley.interop.microstationdgn

using MicroStationDGN;

private MicroStationDGN.Application msApp;

private MicroStationDGN.DesignFile msDGN;

msApp = new MicroStationDGN.Application();

// Works

String DGNLevelName = "ClipShape";

MicroStationDGN.Level dgnLevel = msApp.ActiveDesignFile.Levels.Find(DGNLevelName);

// Works

MessageBox.Show(dgnLevel.ID.ToString());

MessageBox.Show(dgnLevel.Name.ToString());

MessageBox.Show(dgnLevel.Description.ToString());

// Works (Focus in Levenmanager switch to ClipShape)

dgnLevel.IsActive = true;

// Problem part

String newName = "Clip";

dgnLevel.Name = newName;

// Works (Levelmanager reloads)

msApp.ActiveDesignFile.Levels.Rewrite();

........................................

At this - dgnLevel.Name = newName;

i alway got a „Level-ID is invalid“.

Same is if i try - dgnLevel.Description = newName;

Debugger gives me a „Level-ID is invalid“.

I have tried some other tests, like:

msApp.ActiveDesignFile.AddNewLevel("Demo_1");

or

msApp.ActiveDesignFile.DeleteLevel("Demo_1");

All works fine.

Whats wrong with my code or the „ string Name { get; set; } “

Thank you

Harry