How to add custom fields in mobile app

For Appointment screen (Screen ID: FS300200) we added two fields in details tab.

This is working fine on web.

I wants to add it it in mobile app (next to Target Equipment ID).

I tried various code but none of this working (no error - new field not visible)

update screen FS300200 {
  update container "Details"{
    update group "TargetEquipmentGroup"{
		update layout "EquipmentLine" {
		  add field "UsrBuilding" {
			displayName = "Target Equipment Building"
			placeAfter field "TargetEquipmentID"
		  }
		  add field "UsrFloor" {
			displayName = "Target Equipment Floor"
			placeAfter field "TargetEquipmentID"
		  }
		}
    }
  }
}

and

update screen FS300200 {
	update container "Details"{
		update group "TargetEquipmentGroup"{
			add layout "EquipmentDetails" {
				displayName = "EquipmentDetails"
				layout = "Inline"
				add field "UsrBuilding" {
					displayName = "Target Equipment Building"
				}
				add field "UsrFloor" {
					displayName = "Target Equipment Floor"
				}
			}
		}
	}
}

FSAppointmentDet DAC extend for UsrBuilding and UsrFloor field.

String field with no special attributes.

Can anyone have idea how to add custom fields in mobile app?