Problem with screen sharing on iphone

[YiliXia]

I have checked previous post and I am certain that the meeting I am hosting has turned off  "Disable desktop screen sharing". 

I don't see a "share" button on my iphone and I have zoom updated the newest release and also my ios system.  What is the reason for that? Above all, I am the host and I still cannot share the screen! 

My current zoom version is 5.16.6 (11209) .