Confirm your battery isn't dead using a different carto or even a meter if you can.
Is it a manual or an auto battery? manual has a little button that you push to vape. autos, you just suck on them to vape.
If you have an auto battery, be very careful and neat with your juice...blow through and wipe the cartos good before attaching them, and never fill or drip into the carto while it is on an auto battery (untill you get very good at it and know exactly where it'll go).
Next, drip just one or two drops in the tiny hole at the threaded end of the carto and let it sit a minute. Wipe the carto good and clean (the threads too). This process will ensure the atty inside is wet.
Does it vape now? Can you hear a little sizzle inside the carto?
If so...good news...you just need more juice in your cartos
If not...
Could be that the cartos are just bad. Bad batches of cartos do happen sometimes.
Could be that the little post at the end of the carto isn't making good contact with the battery. This can happen from screwing cartos onto the battery too tightly...it simply shoves the contact of the battery down over time...or of the cartos if they have a post in them that can move.
Some cartos have a little post that you can gently tug out with a small tool. You can also try that on your battery, but I'd try a carto that is known to work before messing with the battery contact.