If books are in the appdef file but cannot appear in the interface. how to solve it?

<books id="C01">
    <book-collection-name>Main Collections</book-collection-name>
    <book-collection-abbrev>AVB</book-collection-abbrev>
    <book-collection-description>Alkitab Versi Borneo</book-collection-description>

i have this, but can’t appear in the interface

Hi Elan,
Welcome to the community!
I need to ask a few, clarifying questions:
Do you have only the one book collection in your app?
Do you have books added to the collection?
What appears in the Viewer tab if you click on a book in SAB.
If you build an APK and install on your phone, what are you seeing when you run the app, if anything?
Thanks,
Andrew

hello, andrew

thanks for replying.

I’ve managed to see the books in my project.

I’m missing the letter s on the closing of the books

</book> -> </books>