Deleting events .NET

I'm trying to delete single events, but I'm having problems. This is
what I do:

1) I send a FeedQuery.Query to Google
2) Retrieve the events
    Dim myResultsFeed As AtomFeed = myService.Query(myQuery)
3) Take first event (for example)
    Dim firstMatchEntry As AtomEntry = myResultsFeed.Entries(0)
4) Delete it
   firstMatchEntry.Delete()


It is done with no problems. But when I go to my calendar, I can still
see it on there. Why it is not deleted?

After ten minutes, it seems to be deleted from my calendar. But when I
execute my code again, the firstMatchEntry is again that event!!! So
when I try to delete it, of course, I get an error.

How can I delete events forever? Is there a solution to clean a
calendar, I mean, delete all events in a calendar?

Thanks.