An error occurred regarding team settings and scoreboard.

What I'm making is like this.

Click on the team in the book. (I solved it by clicking)
You get the team of your choice, but you cannot join if you already have a team or there are more than 2 people on the team.
3.red is a team, and there are individual score boards red1 and 2 below, and if there is a person in red1, they are added to red2, otherwise they are added to red1.

I chose the base as one virtual player.
The problem I have now is 

I clicked on the team and the message “Team is already full” appeared.
I changed something, but the message “Already has a team” appeared.
I changed something again (I don't even understand what I did), but no message appears and there is no change in the scoreboard (it's still 0).

I've been trying to fix it for several days now, recreated it, changed the location of "has_team", and changed the value range, but it didn't work. If anyone has any eye problems, please advise me...
It's so difficult that I'm posting it here even in the early morning. (It may be daytime in your area.)
If you can't understand because my translator isn't working well, please tell me.