Personal Image not working for Vuforia

I am trying to work on Vuforia and followed step by step for some tutorial Videos. Still I am unable to get Image detection for Image targets I have uploaded and Database downloaded from Vuforia site. But in case I use default Database I get the detection and everything works fine.
I am sure I am missing something really basic else it would have been mentioned in tutorials. Also 2-3 yr back I tried my hand on Vuforia and it worked then so whatever I am missing has to do something with the version updates (which I understand is quite a lot to start with)
For Image, Augmentable Rating is 4 Star thus detection issue is not concerning that

Working on : Unity 2017.2.0f3 (64-bit)
Testing on : Android Mobile

In top bar of unity there is Vuforia tab, you have to activate the database from the configurations/settings in there.

To anyone facing the same problem in 2021.
To solve this, you need to generate a license key and add it in the Vuforia Configuration Tab. This worked for me at least…