what‘s wrong with this code？
Sun we may need to have more details as just with the pictures it's hard to debug the issue. Please add more details like what you're trying to do, where you getting error, share your codes and then someone can helpful you out.
NullReferenceException means that Part is null.
You might have 2 sessions of SolidWorks running, with the second one not visible.
Check in the Windows Task Manager
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