click the squad tab and then scroll down. sometimes when you have 22 players and you buy a new players it will not show on page and since the total players allowed are 22, the 23rd player won't be included into the team but will show in the squad tab. so sell one player and then pay for the player you just brought. sometimes this can happen and you must be careful since he will be there for only 7 days. if you don't put him in the squad after seven days he will be back for sale.