I have 4 U21 players in my main squad, 2 in my reserve squad, 8 in my Youth center. How can I start U21 squad? I need to promote the players in the Youth center to the reserve squad?

Hi trikotrako.

You need to promote players to the reserve squad before you can use them in the U21 squad.

What are you doing with 8 in your youth center??? Get them out of there by offering them all contracts. And if you can't afford them, or their isn't room in your squads, put some players on the market to make room.