My newest hen acted the same way when she first met a too. She'd never seen a too in her life until we picked her up. She avoided him for weeks. If that is indeed the problem, then your hens may take time to get used to the idea of roos. It may also be less stressful if you start with only one...
Are your hens used to roos? The hens may be fighting them because they aren't used to being mounted or may have never even seen a too. That could be a big part of it.