I can't control my Mac with my iPhone

Hi,

I have a problem with my mac. 

Whe I start teamviewer on my iphone x, I can view my Mac Screen but I can't control it. I Can't use mouse cursor.

I have a second macbook. Here, no problem. When I want control it with my Iphone x, that's all right. I Think depend on Team Viewer new version installed on my Mac (15.x)

May you help me?

Thanks!

Alessio