It's often that some tags don't respond correctly to the proxmark commands.
One very common problem is that the tag is actually too close to the antennas of the proxmark.
In this case, the trick is very simple: just place a "spacer" between the antenna and the tag, and run your commands again.
You like the #pentestips?
Make sure to subscribe to our youtube channel and keep visiting LAB401.com
Do you have #pentestips to submit yourself?
We would love to partner with you, contact us at email@example.com