So I am making so when you click on a sign it opens a gui for you.
This is my current code:

Code (Skript):

1. on right click on sign:
2.     1st line of clicked block is "&0[&5TreinTickets&0]"
3.     open chest with 3 rows named "{@menu-naam}" to player
4.     wait 1 tick
5.     set {_slot} to 0
6.     loop 28 times:
7.         format slot {_slot} of player with 160:5
8.         add 1 to {_slot}
9.     format slot 13 of player with paper named "&5Trein Ticket" with lore "&7Klik op mij om een trein ticket te krijgen!" to close then run [execute console command "/giveticket %player%"]

This is the error I get:

Code (Skript):

1. [12:51:37 ERROR]: 'player with 160:5' is not an item stack (ticketsysteem.sk, line 15: format slot {_slot} of player with 160:5')

and when I click the sign. Nothing happens