Question ARcoreImg- Failed to Add Some of The Image Database

Hi, may I ask about this problem? how to resolve this problem.
Is there a step I'm wrong in Build AR Image Tracked apk?.

I'm very curious about this problem.
Previously when I entered my finished AR Image Tracked application, the application kept force closing.

But now, after I've tweaked it, it's adding a new problem.
In the console there is an error ARcoreImg "failed to add some of the image database"

I don't know what to do anymore, it feels like I want to give up on making this AR project.
Actually, I'm still new to using the Unity Engine, and I don't have a basic programming language at all.

So I just followed the tutorials on YouTube and read some posts on the forum about AR Unity.
I have followed all the steps.

And the result is that, if you don't force close, it fails to add some to the image database+Failed to get enough keypoints from the target image.

Is there something I missed in the tutorial?

Is AR Image Tracked really that hard to make?
Even though I kept repeating it until now and there was absolutely no gap at all.

Sorry, I'm even venting here.
And also sorry, if my writing is a bit weird, because I used google translate here.