为什么 C64 Basic 的第 6 行会出现意外字符？

问：

PRG Studio 表示第 6 行有一个意想不到的字符。但是，我不明白为什么。我正在为 c64 编程。

1 rem setup
3 holding = "nothing"
6 playing_game = true
10 rem intro
20 print "it is dark. you have hiked miles to get here."
30 gosub 10000 rem wait
40 print "you have come to explore the castle of chadon hill."
50 gosub 10000 rem wait
60 print "it is said to have many traps. it is abandoned."
70 gosub 10000 rem wait
80 print "nobody has ever came back out..."
90 gosub 10000 rem wait
10000 rem wait
10010 waitcount = 0
10020 while waitcount < 50: waitcount = waitcount + 1: next waitcount
10030 return

我试图将“”更改为“”，但这不起作用，我尝试将 true 更改为“true”。那什么也没做。