Mirroring from IPhone 11 Pro Max

Trying to mirror from IPhone 11 Pro Max to the pico max.
Was using the directv app on my phone to mirror to projector. Starts to work then the screen pops up a response of HDMI not supported.

But I have nothing connected to the HDMI plug as I am mirroring.

Seems display pictures from my library.

What am I doing wrong??