did you clean your battery/atty connection?...every so often it gets lousy..and if you just take a tissue and clean the
threads of the atty..and then kinda swist a point and clean the inside of the battery
threads..you'll be surprised at how much crud comes out...and then screw them together again..if the connection is kinda crap you wont get much vapor..
EDIT: usually it's my battery thats kinda crudded up...so I clean it and screw em back together and I'm usually good..
Could also be the
juice if you're using something thick and dark and full of particulate..