I agree with ilporcupine.
Could be a bad coil. Replace the coil in the tank after priming it with e-liquid. If you don't know how to prime a coil properly, ask how.
Check the 510 connector on your battery device. If dirty with spilled e-liquid, clean it with denatured alcohol and a cotton swab. Sometimes the center pin of the 510 connector is forced into the mod from overtightening the tank onto the battery device. Often you can "tease" the center pin up higher so that it can make an electrical connection to the tank.