Web Client URL von NAV 2017

Hi everybody,

I've installed NAV 2017 parallelly to NAV 2016, including the Web Client.
The URL for NAV 2016 is http://localhost:8080/DynamicsNAV90/WebClient, and it's working fine.
But when I enter http://localhost:8080/DynamicsNAV100/WebClient, it's not working for NAV 2017.
Has anybody an idea, what may be missing? In my folder "C:\inetpub\wwwroot\", the structure looks the same for NAV 2016 and NAV 2017.

Thanks in advance,
Frank