Searching contact Skype for Business

Hi,

We have Polycom's Group 500 witn Touch pannel and we are using it in Skype mode. Skype meeting works, calendering works, but when I search a contact to add it into the meeting, some people are not in the search result, and some are. If I search Martin by exemple, it will give me a list with all persons with Martin in their name. Michel or Jean will show nothing.

Also, every contacts in the search result have an "Unknow" under their name. How do I fix that?

Thank you

Running 6.1.1