Unable to substitute an outfield player during gameplay

Hello everyone,I'm playing SWOS 7.7 on Windows and I'm having trouble substituting injured players—or any players—during a match. Changing tactics during the game works without any issues. However, when I try to make a substitution, I can select the player I want to take off, but no replacement players are shown. As a result, the substitution can't be completed and has to be cancelled.Often, the player I intended to substitute ends up with a kind of white diamond shape above his head. I'm honestly a bit lost and would really appreciate any help. Thank you!Wishing you all a pleasant afternoon.Best regards, Crunsh

Alright! I’ve finally found the manual and now I know that the manager obviously isn’t a substitute player loooool Sorry folks! I’m clearly not worthy

Cheers, Crunsh