Contact Group / Invitation - personalized report

Hello,

i just started with community surveys:

I created my first survey as "private" and "onymous" survey.
I created a contact group called "employees" and added myself as contact.
Then i manually started the cronjob and received the email for the survey.
To have access to it i changed the permissions for public people.

By now everything except one thing is going fine:
When i look at the report of the finished survey it's not my name in there, it's "Guest". I thought when i'm inviting via contact group the survey report will have the personalized information about the customer i invited through the contact group. How can i make this possible?

Thanks in advance.