Object vanished before it is removed?

FROM : Knut Lorenzen
DATE : Sun Feb 10 20:18:36 2008

Hi all,

I am trying to loop through an NSMutableArray of 
NSMutableDictionaries, extract archived NSColors, convert them to 
hexValues and then remove the NSColor from the NSArray. Here's the code:

int row;
for (row = 0; row < [theArray count]; row++) {
   NSMutableDictionary *testDic = [NSMutableDictionary 
dictionaryWithDictionary: [theArray objectAtIndex: row]];

   NSColor *bgColor = (NSColor *)[NSUnarchiver unarchiveObjectWithData: 
[testDic valueForKeyPath: 
@"OUTPUT_WINDOW_SETTINGS.NSBACKGROUND_COLOR"]];

   [[testDic valueForKey: @"OUTPUT_WINDOW_SETTINGS"]
           setObject: [bgColor hexadecimalValueOfAnNSColor]
               forKey: @"BACKGROUND_COLOR"];

   NSLog(@"%@ has the value %@", [testDic valueForKey: @"NAME"] , 
[testDic valueForKeyPath: 
@"OUTPUT_WINDOW_SETTINGS.NSBACKGROUND_COLOR"]);

   [[testDic valueForKey: @"OUTPUT_WINDOW_SETTINGS"] removeObjectForKey: 
@"NSBACKGROUND_COLOR"];
}

The problem is, after the first loop, the log reads:

Testdata1 has the value <040b7374 7265616d 74797065 6481e803 84014084 
8484074e 53436f6c 6f720084 84084e53 4f626a65 63740085 84016301 
84046666 66660000 010186>
Testdata2 has the value (null)
*** -initForReadingWithData: nil argument

But Testdata2 does exist and has the appropriate value (checked with 
NSLog). What am I missing?

Cheers,

Knut