shielding and blocking apps

i'm trying to shield and block apps on child device.

i managed to block apps by creating a  variable blockedApps : Set = Set() that contains a list of applications like Application(bundleIdentifier: "com.apple.calculator") inside the intervalDidStart on my DeviceActivityMonitor extension

now i'm trying to shield an app using the same extension and nothing happens. for this i used this code inside intervalDidStart:

  let calculatorApp = Application(bundleIdentifier: "com.apple.calculator")     var blockedApps : Set = Set()           guard let token = calculatorApp.token else {       return     }     blockedApps = [token]     store.shield.applications = blockedApps

and i cant tell what is the reason for this not working

1. is there a token issue that is nil?
2. does shielding requires a different app extension?
3. does my app extension requires some additional configuration maybe a different NSExtensionPointIdentifier?