Opening emails after check returns an error

[Yokiie]

In the following code :

＊OnBIFFComplete
＞メールがない【タブ】（Ｒ０）==0
\t\h\_q（Ｒ２）
（Ｒ０） mails ／（Ｒ１） Byte(s)
\_qYou've got e-mails。

＿Open e-mails
＿Do nothing

If you select "Open e-mails", you get the following error : "The dialogue option 「Open e-mails」 doesn't exist。 Description error？"