Memory Leak with Plist Serialization

Please help me with this memory leak. In the leaks tool it shows a leak: NSCFString (32 bytes) in the library Foundation Responsible Frame: NSPropertyListSerialization. I am releasing the error but still a leak. What am I missing? Many thanks!

    NSPropertyListFormat format; 
    NSString *anError = nil;
    id plist;
    plist = [NSPropertyListSerialization propertyListFromData:rawCourseArray mutabilityOption:NSPropertyListImmutable format:&format errorDescription:&anError];
    if (!plist){
          [anError release];
    } 
    NSArray *entries = (NSArray *)plist;
    for (NSDictionary *entry in entries) 
    {
      // DO SOMETHING
    }