Custom Headers are not working

[yugeshm]

I am using a this library to displays a CollectionView as an asymmetric grid layout.

I am trying to create custom section headers between multiple grids, however the section headers are not displaying even though it creates an empty white space. I am looking to achieve something like this:

Here is my code:

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section {
return CGSizeMake(320, 60);
}