Hi @takehirosakurai,
There is a bug in the Rhino 6 SR1 SDK installer in that it creates the wrong registry key. Try this:
1.) Uninstall the Rhino 6 SR1 SDK
2.) Install this version, which is Rhino 6 SR0.
https://www.rhino3d.com/download/Rhino-SDK/6.0/release
The name of downloaded msi should be rh60sdk_6.0.18016.23451.msi.
Does this help?
– Dale