I could reproduce the "problem" but I could not find why. Usually, you need to add the namespace for an object type if the compiler does not know which namespace should be used. That implies that there is another namespace with the object "Circle" but I could not find such namespace.
But if you are learning VBA then I would advise you to stop and start learning VB.net/iLogic. This is what Autodesk writes about VBA:
"For security reasons, the Microsoft VBA module is not included in the Inventor installer. It has a dependency on the Visual Studio 2010 (VC10) runtime, which Microsoft will not support after July 2020."
and
"As an alternative to VBA, consider using Inventor’s iLogic capability. It provides access to the Inventor API using VB.NET."
That sounds to me like the end of VBA and not something that I would put any effort in.
Jelte de Jong
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