Was it your first cartridge? It sounds like it could (possibly) be a manufacturing defect, but I'm not too knowledgeable about this setup. If you have a reasonably proficient vape store anywhere near you, you might take it in, to make sure it's not some sort of user error (and I'm sure you'll get great suggestions from others) but if it's under warranty, well, take it in, or watch a youtube video or two about your device, not so much for the review but how to operate it properly.
If none of these remedies bear fruit, you may need to consider a warranty. Sorry to not be of more help. Good luck!
Anna