无法将事件保存在iPhone的eventkit上

EKEventStore *eventStore = [[EKEventStore alloc] init];
EKEvent *newEvent = [EKEvent eventWithEventStore:eventStore];

NSDateFormatter *   dateFormatter = [[NSDateFormatter alloc] init];
[dateFormatter setDateFormat:@\"yyyy-MM-dd:HH:mm\"];

NSString *fechainicio = @\"2011-04-13:22:30\";
NSString *fechafin = @\"2011-04-14:24:00\";

NSDate * date = [[NSDate alloc] init];
date = [dateFormatter dateFromString:fechainicio];
NSDate * date2 = [[NSDate alloc] init];
date2 = [dateFormatter dateFromString:fechafin];

[date2 retain];
[date retain];
[fechainicio retain];
[fechafin retain];

newEvent.title = @\"title\"; 
newEvent.startDate = date;
newEvent.endDate = date2;

[newEvent setCalendar:[eventStore defaultCalendarForNewEvents]];
NSError *err;
[eventStore saveEvent:newEvent span:EKSpanThisEvent error:&err];

if (err != nil)
{
    NSLog(@\"error\");
}