startGeofencingAsync Expo Locations

Hi,
I am trying to implement geofencing but having this error
[Unhandled promise rejection: Error: java.lang.Double cannot be cast to java.lang.String]
below is my code please guide me what am doing wrong

componentDidMount() {
let region = { identifier: 1, latitude: 25.3036015, longitude: 55.3670917, radius: 20 }
Location.startGeofencingAsync(“geoFence”, [region])
alert(‘12’)
TaskManager.defineTask(“geoFence”, ({ data: { eventType, region }, error }) => {
if (error) {
alert(“here un error”)
// check error.message for more details.
return;
}
if (eventType === Location.GeofencingEventType.Enter) {
alert(“You’ve entered region:”, region)
console.log(“You’ve entered region:”, region);
} else if (eventType === Location.GeofencingEventType.Exit) {
alert(“You’ve left region:”, region)
console.log(“You’ve left region:”, region);
}
});

}