Hello @Sicheng_Zhu,
Welcome to the forum, feel free to introduce yourself.
That’s awesome that you’re are trying to develop your own connector! Which program are you developing it for?
We need a bit more info in order to help you with this issue. If you look at our most updated code for DUI2, you can see that MainWindow implements MainViewModel, not MainWindowViewModel. We used to use a MainWindowViewModel, but we’ve refactored our code a bit. So depending on when you forked our code, MainWindowViewModel not being recognized may be the correct behavior, not an issue.
If you do have an existing MainWindowViewModel then you’ll have to post some code for us to help us see where things are going wrong.