Test Active Transponder Battery Life to see if the voltage is within a usable level. Transponders with batteries at or below 2.3 volts should be replaced.
If you have transponders that are labeled, verify that the labels are still in good, readable condition and they are not falling off.
Keep transponders stored in a metal container away from anything with a radio signal or anything that can cause radio interference. We offer a specific container for this in our shop here.

Check all of your Active Transponders to see if the batteries are almost dead. Running a fridge or freezer test as described in this article will help you determine if your transponders are dead or not.