Strange interaction with NSPastboard and TextEdit

Question

I am dragging a string from two places in my application. One of the custom NSViewand one of the delegate NSTableDataSource. The first allows me to drag text into a TextEdit application, and the second does not. I can drag from both to other applications, such as Terminal or TextMate. As far as I can tell, I use close to identical code for both.

I'm trying to understand what happened. This works in principle because I can drag and drop into some applications. But what happens with TextEdit?

From custom NSView:

(void)mouseDown:(NSEvent *)theEvent
{
    NSString *testString = @"TEST";

    NSImage *dragImage;
    NSPoint dragPosition;

    NSPasteboard *pboard = [NSPasteboard pasteboardWithName:NSDragPboard];

    [pboard declareTypes:[NSArray arrayWithObjects: NSStringPboardType, nil] owner:nil];
    [pboard setString:testString forType:NSStringPboardType];

    dragImage = // blah
    dragPosition = [self convertPoint:[theEvent locationInWindow] fromView:nil];

    [self dragImage:dragImage
                 at:dragPosition
             offset:NSZeroSize
              event:theEvent
         pasteboard:pboard
             source:self
          slideBack:YES];
    }
}

From the table delegate:

(BOOL)tableView: (NSTableView *)aTableView writeRowsWithIndexes: (NSIndexSet *)indexes toPasteboard: (NSPasteboard *)pboard
{
    NSString *testString = @"TEST";

    [pboard declareTypes:[NSArray arrayWithObjects: NSStringPboardType, nil] owner:nil];
    [pboard setString:testString forType:NSStringPboardType];

    return YES;
}

If I print the pboard types for the first:

"public.utf8-plain-text",
NSStringPboardType,

And for the second:

"public.utf8-plain-text",
NSStringPboardType,

Similarly, the contents for the first:

2010-11-16 13:56:01.832 XXX[1654:a0f] public.utf8-plain-text:TEST
2010-11-16 13:56:01.838 XXX[1654:a0f] NSStringPboardType:TEST

And second

2010-11-16 13:56:05.623 XXX[1654:a0f] public.utf8-plain-text:TEST
2010-11-16 13:56:05.623 XXX[1654:a0f] NSStringPboardType:TEST

So, as far as I can tell, they should behave the same. But this is not so. Ideas?