You may have screwed it on the battery too tightly and pushed the center pin of the CE4 in a little too far. Someone already suggested moving the battery center pin, but I'd give that a try on the center pin of the CE4 instead, just for ....s and giggles. I'm not familiar with the CE4 but would suspect that the center pin can be moved out a little to improve the connection. If that doesn't work, it is ferme.
I you're using sweet liquids, that can shorten the life of any atomizer due to "gunk" buildup.