Why doesn't my calendar alert me when events are upcoming? I have my Google Calendar synced up to my iPhone 4S and by all the settings I can find, it looks like I am supposed to recieve alerts 15 minutes before every event.  However, this has never happened.

How come there is no alert being displayed when an event is upcoming?  I can see it in Notification Centre, but there is no banner or alert.
Something that seems to work for Google calendars: on your phone, go to Settings => Mail, Contacts, Calendars. Scroll down to the Calendars block. Select Default alert times. You can then chose phone alerts by type of event.