Use FSEvents in a stand-alone application

I am trying to use FSEvents in my isolated application to control some directories. I performed the following class:

@implementation SNTracker

- (id)initWithPaths:(NSArray *)paths {
    self=[super init];
    if (self) {
        trackedPaths=paths;
        CFTimeInterval latency=1.0;
        FSEventStreamContext context={0,(__bridge void *)self,NULL,NULL,NULL};
        FSEventStreamRef eeventStream=FSEventStreamCreate(kCFAllocatorDefault,&callback,&context,(__bridge CFArrayRef)trackedPaths,kFSEventStreamEventIdSinceNow,latency,kFSEventStreamCreateFlagUseCFTypes|kFSEventStreamCreateFlagWatchRoot|kFSEventStreamCreateFlagFileEvents);
        FSEventStreamScheduleWithRunLoop(eeventStream,[[NSRunLoop mainRunLoop] getCFRunLoop],kCFRunLoopDefaultMode);
        FSEventStreamStart(eeventStream);
    }
    return self;
}

static void callback(ConstFSEventStreamRef streamRef,void *clientCallBackInfo,size_t numEvents,void *eventPaths,const FSEventStreamEventFlags eventFlags[],const FSEventStreamEventId eventIds[]) {
    NSLog(@"asd");
}

The problem is that "asd" is never printed (that is, the callback function is never called). When I turn off “Enable Application Sandbox” in the summary of my main goal in Xcode, the call invokes the call. Am I doing something wrong? The only right that I have granted to the isolated software is read and write access to the files selected by the user.