My father can't see my screen on FaceTime

Today I was on my facetime call wiith my father. Then I decided to share my screen. BUT THERE WAS SOME RANDOM ST*PID(Not working) APP TO LITERALLY SHARE MY SCREEN. I tried to use it but realized ITS NOT WORKING. I decided to restart and then call. But when I called him after restarting, the app was not there. aND then I click the screen share And it shows that I am screen sharing. BUT MY FATHER CAN'T SEE IT.

:((

SOMEBODY PLS TELL ME IF MY DEVICE IS NOT WORKING OR MY FATHER'S DEVICE(an iphone) IS NOT WORKING.(pls do not report me using swear words...... I censored it)

[Re-Titled by Moderator]

Original Title: SHARING MY SCREEN