Problems with image recognition on HoloLens

Hi,

I am whole new in the topic of AR. And of course I already got my first problem where I couldn't find any help in the internet.

At the moment I'm trying to get to work a simple image recognition with Vuforia. At the first step on webcam, everything worked, as expected.

In the next step I was trying to use it on the HoloLens where most tutorials show some clicks and everything's done. But it's not in my case.

The connection to the HoloLens is working and it's showing every object which I put in. But the image recognition is not working. What am I doing wrong?

Can I still use the play function of Unity to try my application, or do I always have to build the app and start it via Visual Studio for image recognition?

I'm working on Unity 2018.2.14f1 in Windows 10. Also I put some screenshots of my (very simple) project in the attachment.

I hope somewone can help me, guess it's a very simple issue but I'm just not able to fix it. ;)