Calling a VI in a LabVIEW DLL as a separate instance

[Edicia]

Hello,

I have a C# application that allows the user to open multiple MDI windows. Each MDI window is an empty parent window for a LabVIEW DLL where the controls and front panel (form) is defined in the main VI of the LabVIEW DLL. Each MDI window opens the LabVIEW main VI on a new thread. If I open four MDI / LabVIEW windows of the same LabVIEW main VI and close them in the reverse order in which they were opened, then everything seems to shut down properly. However, if I open four MDI / LabVIEW windows of the same LabVIEW main VI and close the one that was opened first, then the first window shuts down properly, but the fourth one opened closes only the LabVIEW portion of the window (the child of the MDI) and leaves the C# MDI empty parent window still visible. The LabVIEW DLL is both reentrant (in the VI properties) and AllowMultipleInstances = TRUE (in the .ini file).

So I was wondering if calling this VI in a LabVIEW DLL is truly a multiple instance (since two of my four instances were closed when I only clicked one Close box)?

Or, maybe there is something more I need to do in LabVIEW to be able to run a VI in a LabVIEW DLL as a separate instance each time it is called from C#?