NSPredicate BETWEEN with NSDate causes -[__NSDate constantValue]: unrecognized selector sent to instance 0x1e7ff0

I'm trying to fetch from Core Data records that have a startTime between two dates.

Here's my code:

NSDate *today = [NSDate date];
NSDate *distantFuture = [NSDate distantFuture];

// Create the predicate
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"startTime BETWEEN %@", [NSArray arrayWithObjects:today, distantFuture, nil]];

NSLog(@"today: %@, distantFuture: %@", today, distantFuture);   
NSLog(@"predicate: %@", predicate);

// Add the predicate to the fetchRequest
[[[self fetchedResultsController] fetchRequest] setPredicate:predicate];

NSError *error;
if (![[self fetchedResultsController] performFetch:&error]) 
{
    // Update to handle the error appropriately.
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    exit(-1);  // Fail
}

And here's the console output:

2011-03-11 02:00:03.166 TestApp[2668:307] today: 2011-03-11 01:00:03 AM +0000, distantFuture: 4001-01-01 12:00:00 AM +0000
2011-03-11 02:00:03.174 TestApp[2668:307] predicate: startTime BETWEEN {2011-03-11 01:00:03 AM +0000, 4001-01-01 12:00:00 AM +0000}
2011-03-11 02:00:03.180 TestApp[2668:307] -[__NSDate constantValue]: unrecognized selector sent to instance 0x1e7ff0
2011-03-11 02:00:03.198 TestApp[2668:307] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDate constantValue]: unrecognized selector sent to instance 0x1e7ff0'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x314d0987 __exceptionPreprocess + 114
    1   libobjc.A.dylib                     0x319a149d objc_exception_throw + 24
    2   CoreFoundation                      0x314d2133 -[NSObject(NSObject) doesNotRecognizeSelector:] + 102
    3   CoreFoundation                      0x31479aa9 ___forwarding___ + 508
    4   CoreFoundation                      0x31479860 _CF_forwarding_prep_0 + 48
    5   CoreData                            0x352ed973 -[NSSQLSimpleWhereIntermediate _generateSQLBetweenStringInContext:] + 766
    6   CoreData                            0x35244fff -[NSSQLSimpleWhereIntermediate generateSQLStringInContext:] + 502
    7   CoreData                            0x35244647 -[NSSQLFetchIntermediate generateSQLStringInContext:] + 74
    8   CoreData                            0x352e42b3 -[NSSQLGenerator newSQLStatementForFetchRequest:ignoreInheritance:countOnly:nestingLevel:] + 234
    9   CoreData                            0x352414ab -[NSSQLAdapter _newSelectStatementWithFetchRequest:ignoreInheritance:] + 378
    10  CoreData                            0x35241329 -[NSSQLAdapter newSelectStatementWithFetchRequest:] + 16
    11  CoreData                            0x35241205 -[NSSQLCore newRowsForFetchPlan:] + 288
    12  CoreData                            0x35240531 -[NSSQLCore objectsForFetchRequest:inContext:] + 420
    13  CoreData                            0x35240151 -[NSSQLCore executeRequest:withContext:error:] + 304
    14  CoreData                            0x352d0295 -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 896
    15  CoreData                            0x3523d877 -[NSManagedObjectContext executeFetchRequest:error:] + 374
    16  CoreData                            0x352f541b -[NSFetchedResultsController performFetch:] + 766
    17  TestApp                             0x0001ac6d -[MatchesCalendarDataSource loadMatchesFrom:to:delegate:] + 268
    18  TestApp                             0x0001ad51 -[MatchesCalendarDataSource presentingDatesFrom:to:delegate:] + 68
    19  TestApp                             0x00021353 -[KalViewController reloadData] + 110
    20  TestApp                             0x00021b15 -[KalViewController loadView] + 452
    21  UIKit                               0x338dc227 -[UIViewController view] + 30
    22  UIKit                               0x338e8d0b -[UIViewController contentScrollView] + 22
    23  UIKit                               0x338e8b7b -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] + 30
    24  UIKit                               0x338e8a79 -[UINavigationController _layoutViewController:] + 24
    25  UIKit                               0x338e84d3 -[UINavigationController _startTransition:fromViewController:toViewController:] + 254
    26  UIKit                               0x338e835f -[UINavigationController _startDeferredTransitionIfNeeded] + 182
    27  UIKit                               0x338e82a3 -[UINavigationController viewWillLayoutSubviews] + 14
    28  UIKit                               0x338e823f -[UILayoutContainerView layoutSubviews] + 138
    29  UIKit                               0x338b10cf -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 26
    30  CoreFoundation                      0x3146ebbf -[NSObject(NSObject) performSelector:withObject:] + 22
    31  QuartzCore                          0x30a6c685 -[CALayer layoutSublayers] + 120
    32  QuartzCore                          0x30a6c43d CALayerLayoutIfNeeded + 184
    33  QuartzCore                          0x30a6656d _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 212
    34  QuartzCore                          0x30a66383 _ZN2CA11Transaction6commitEv + 190
    35  QuartzCore                          0x30a89f9d _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 52
    36  CoreFoundation                      0x31460c59 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 16
    37  CoreFoundation                      0x31460acd __CFRunLoopDoObservers + 412
    38  CoreFoundation                      0x314580cb __CFRunLoopRun + 854
    39  CoreFoundation                      0x31457c87 CFRunLoopRunSpecific + 230
    40  CoreFoundation                      0x31457b8f CFRunLoopRunInMode + 58
    41  GraphicsServices                    0x35d664ab GSEventRunModal + 114
    42  GraphicsServices                    0x35d66557 GSEventRun + 62
    43  UIKit                               0x338d5329 -[UIApplication _run] + 412
    44  UIKit                               0x338d2e93 UIApplicationMain + 670
    45  TestApp                             0x000029d7 main + 70
    46  TestApp                             0x00002958 start + 52
)
terminate called after throwing an instance of 'NSException'

I've also tried the predicate below, which uses >= AND <= instead of the BETWEEN statement (see below). This doesn't cause an error but neither does it fetch any records!

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(startTime >= %@) AND (startTime <= %@)", today, distantFuture];

As a test I've tried a predicate that doesn't include NSDate objects and it works fine (see below):

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"location.title == %@", @"Boston"];

Any help or advice would be much appreciated.

Many thanks, Matthew

Edit

Thanks for your help Dave.

So now I'm back to using the <= construct but I'm getting 0 objects fetched.

I was just using today and distantFuture as a test to make absolutely sure that my startTime would be between those dates. In the real code it's a range from fromDate to toDate.

Here's my NSPredicate:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"( ( %@ <= %K ) && ( %K <= %@ ) )", fromDate, @"startTime", @"startTime", toDate];

Here's the console output:

predicate: CAST(336261600.000000, "NSDate") <= startTime AND startTime <= CAST(339285599.000000, "NSDate")
[sectionInfo numberOfObjects]: 0

Here are the dates that are in Core Data (the Attribute Type is set to Date):

startTime
---------
337249800
337309200
337318200

I have no idea why 0 objects are returned. Can anyone see where I'm going wrong?