FM players can't play in the Champions League.

The number of players participating in the Champions League should be reported before the start of the European League. Once the Champions League begins, players who have not signed up will not be eligible to participate in the Champions League. That is to say, you use MU Club, and the number of players who participated in the Champions League in 2007-08 season was reported in August-September 2007. The player you signed in 1 month is not on the list of Champions League players reported by your club, so you are not qualified to represent your MU club in the 07- 0 competition.