Błąd w skrypcie na bilet do metra

Błąd w skrypcie. Jak naprawić błąd piece of paper named "&aBilet od metra" is not a potion.

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# Komenda do otworzenia GUI
command /metro:
    trigger:
        open chest with 1 row named "Kup Bilet do Metra" to player
        wait 1 tick
        set slot 4 of player's current inventory to paper named "&aBilet do Metra" with lore "&7Cena: &a5$"
        set slot 6 of player's current inventory to paper named "&a15-minutowy Bilet do Metra" with lore "&7Cena: &a10$"

# Obsługa kliknięcia na bilety w GUI
on inventory click:
    if inventory name of player's current inventory is "Kup Bilet do Metra":
        cancel event
        if clicked slot is 4:
            if player's balance is greater than or equal to 5:
                remove 5 from player's balance
                give player 1 paper named "&aBilet do Metra"
                close player's inventory
                send "&aKupiłeś bilet do metra!" to player
            else:
                send "&cNie masz wystarczająco pieniędzy, aby kupić bilet." to player
        if clicked slot is 6:
            if player's balance is greater than or equal to 10:
                remove 10 from player's balance
                give player 1 paper named "&a15-minutowy Bilet do Metra"
                close player's inventory
                set {metro::15min::%player%} to now
                send "&aKupiłeś 15-minutowy bilet do metra! Bilet jest ważny przez 15 minut." to player
            else:
                send "&cNie masz wystarczająco pieniędzy, aby kupić 15-minutowy bilet." to player

# Blokowanie dostępu do wagoników bez biletu
on right click on minecart:
    if player does not have paper named "&aBilet do metra" and player does not have paper named "&a15-minutowy Bilet do Metra":
        cancel event
        send "&cMusisz mieć bilet do metra, aby wejść do wagonika." to player
    if player has paper named "&a15-minutowy Bilet do Metra":
        if difference between {metro::15min::%player%} and now > 15 minutes:
            remove 1 paper named "&a15-minutowy Bilet do Metra" from player
            delete {metro::15min::%player%}
            send "&cTwój 15-minutowy bilet stracił ważność." to player
            cancel event
        else:
            send "&aMożesz wejść do wagonika. Twój bilet jest ważny." to player
            remove 1 paper named "&a15-minutowy Bilet do Metra" from player
    else if player has paper named "&aBilet do Metra":
        send "&aMożesz wejść do wagonika." to player
        remove 1 paper named "&aBilet do Metra" from player

# Usuwanie przeterminowanego biletu
every 1 minute:
    loop all players:
        if {metro::15min::%loop-player%} is set:
            if difference between {metro::15min::%loop-player%} and now > 15 minutes:
                remove 1 paper named "&a15-minutowy Bilet do Metra" from loop-player
                delete {metro::15min::%loop-player%}
                send "&cTwój 15-minutowy bilet do metra stracił ważność i został usunięty." to loop-player