Haptic API example not working

Hi, I’m new to React Native and Expo. I was exploring the API available and wanted to give the Haptic one a try.
https://docs.expo.io/versions/v39.0.0/sdk/haptics/#hapticsnotificationasynctype

I tried to run on load, and onPress of button, but neither worked.

I used Haptics.notificationAsync(Haptics.NotificationFeedbackType.Error)

I tried on my iPhone device, no error nor Haptic. Am I missing anything? Thanks!