Error while doing FQLRequest

Question

I am doing a FQL request when in my view controller through a specific method. Here is my request.

NSString* fql = [[NSString alloc] init];
fql = [NSString stringWithFormat:@"SELECT uid, name FROM user WHERE uid IN(SELECT uid FROM event_member WHERE eid= %@) AND sex='female'", event_id];

    NSMutableDictionary* params = [NSMutableDictionary dictionaryWithObject:fql forKey:@"query"];
    [[Facebook shared] requestWithMethodName:@"fql.query" andParams:params andHttpMethod:@"POST" andDelegate: self];
        [fql release];

However, when I just launch my request a second time, I got that error when using NSZombieEnabled :

-[CFString release]: message sent to deallocated instance 0x4cb9ec0

The thread points at [_params release] in FBRequest.m

When trying just changing the request with

    fql = @"SELECT uid, name, sex FROM user WHERE uid IN (SELECT uid2 FROM friend WHERE uid1 = me()) AND sex = 'male'";

I have no longer the error.

Here are the fbrequest delegate methods

- (void)request:(FBRequest *)request didReceiveResponse:(NSURLResponse *)response {
    NSLog(@"FBRequestDelegate Received response");
}

- (void)request:(FBRequest *)request didLoad:(id)result {
    NSLog(@"FBRequestDidLoad Received response");
    self.allListProfils = result;
    NSLog(@"all listprofil :%@", allListProfils);
    [self resetSearch];
    [DSBezelActivityView removeViewAnimated:YES];
    moreButton.hidden = NO;
    [table reloadData];
};

- (void)request:(FBRequest *)request didFailWithError:(NSError *)error {
    NSLog(@"FBRequestDidFailWithError Received response, Error is : %@",[error description]);
};

Does it ring a bell for some of you ?

Thanks :)