Subscribe isn't working

using { /Fortnite.com/Devices }
using { /Verse.org/Simulation }
using { /UnrealEngine.com/Temporary/Diagnostics }
using { /Fortnite.com/Characters }

See Create Your Own Device Using Verse for how to create a verse device.

A Verse-authored creative device that can be placed in a level

Invisibility_device := class(creative_device):

@editable
TriggerDevice : item_granter_device = item_granter_device{}

@editable
ToggleDelay : float = 15.0


ItemGrantedEvent(P : agent) : void =
    spawn:
        Invisibility(P)

Invisibility(P : agent)<suspends> : void =
    if (F := P.GetFortCharacter[]):
        F.Hide
    Sleep(ToggleDelay)
    if (f := P.GetFortCharacter[]):
        f.Show

# Runs when the device is started in a running game
OnBegin<override>()<suspends>:void=
    TriggerDevice.ItemGrantedEvent.Subscribe

You must write it this way:

TriggerDevice.ItemGrantedEvent.Subscribe(ItemGrantedEvent)

Thank you