Notary for the Invitation Letter

Hey guys,

May I ask a question about the notary for the invitation letter for the visa application?
I am helping my parents to apply for a visa to visit Switzerland.

We are required to provide the notary for the invitation letter..
We did it in my home-country's embassy and it was rejected.... And I was told to provide the notary of the invitation letter from a Swiss local notary.

Do you have any experience on this?
I plan to do it here as I live in Zollikerberg
http://www.notariate.zh.ch/Riesbach-Zuerich/

Thanks for the suggestions!

Best,