Training for new position greyed out on patch 15.3.0

Hi. I am playing as FC Porto and have a couple of players that I want to train into a new position but the function is greyed out on the develop screen.

Any ideas anyone?

Thanks

I had the same problem but after a while I understood that I asked to the assistant-manager to organise the individual trainings thats why you can't retrain them, so you just have to speak to your assistant and tell him that you will do the individual trainings yourself, at least that was my problem. You might have another problem.

That's great thanks mate. It now works.