"collection element of type BOOL" is not an objective-c object

Anyone have a clue why I am getting this?

-(void)postPrimaryEMWithEM:(EM *)em
              exclusive:(BOOL) isExclusive
                 success:(void (^)())onSuccess
                 failure:(void (^)())onFailure {


if(self.accessToken) {


    GenericObject *genObject = [[GenericObject alloc] init];

    [[RKObjectManager sharedManager] postObject:genObject
                                          path:@"users/update.json"
                                    parameters:@{
                                                  ...
                                                 @"em_id"  : ObjectOrNull(em.emID),
                                                 @"exclusive": isExclusive  <-- error message