Input System "ButtonControl" variable not recognized

I am trying to use user input strings to reference controls.
for instance …
if ((ButtonControl)(Gamepad.current["buttonSouth"]).isPressed) Debug.Log(Gamepad.current[button]);

This looks like it should cast the Control Type to ButtonControl to access the method “isPressed”
but unity doesnt recognize the ButtonControl type.

I wasnt using the correct namespace

using UnityEngine.InputSystem.Controls;

it works as expected with this namespace