MapKit Zoom Not working

As soon as I add an annotation and go back to the menu it no longer zooms in. However if there are no annotations it will zoom in every time. This is where I add an annotation from Core Data.
for myLocation in myLocations {
if (myLocation.date! >= WeeklySpan(increment: myValue)){
let annotations = MKPointAnnotation()
annotations.coordinate = CLLocationCoordinate2D(latitude: myLocation.latitude, longitude: myLocation.longitude)
annotations.title = myLocation.detail
mapView.addAnnotations([annotations])
myCount -= 1
print(myValue)
print(myCount)
print(myLocation.date! as Any)
print(WeeklySpan(increment: myValue))
}

        }
        return mapView