Mobile keyboard direction

There are some scenes in my app in landscape direction. The other scenes are in portrait direction.

I need to use mobile keyboard with those scenes, but the keyboard always shows in portrait direction.

I thought it was simple, but I was wrong.

No matter how I try, it still shows in portrait direction.
I wonder how to make the keyboard in landscape direction.

Can anyone help me out on this issue?
Thanks in advance for any help.

On each scene, switch the screen orientation from script, giving the information to the device on how to show controls and task bars :

Screen.orientation = ScreenOrientation.Landscape;
Screen.orientation = ScreenOrientation.Portrait;