Can anyone put me in the right direction, please?

Hello,

I have trouble selecting a machining method (strategy) to finish cut a fillet on this training part. I also wish to clean up the smaller OD at the same time and with the same tool.

The model's fillet is R4 mm and my tool is a 7,42mm (R3.71 mm) Ball end mill and when I try Pencil Tracing, Valley Remachining, Curve Machining, Between 2 Curves Machining bla, bla, bla....it just returns a message: "Null reference error" or "Error creating toolpath" etc..

What is wrong here? Can anyone put me in the right direction, please?

Please help.

I didn't find the right solution from the internet.

References:
https://mecsoft.com/phpbb/viewtopic.php?t=2033
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Thank you.