C# library not allowing selection when using ShowDialog

[MShetty]

I have currently developed a CATIA library using C#. This C# dll is referenced in VBA, and used to run some functions.
I also have designed some userforms in the library.
The current issue that I am facing is when I use ShowDialog() method on the UI, I am unable to use Selection methods like SelectElement2.
The only work around for this is to do a userform.show().
Does anybody know why this happens and how I can still use ShowDialog() and SelectElement2()?

 

[Little Cthulhu]

Check documentation on SelectElement methods - it explicitly states that you aren't allowed to use it with forms displayed.

Try displaying c# form with Application.Run.