I have been using Blu vapes for about 2 years now. Too many times I have bought refills and 1 of the 2 refills does not work. Finally, yesterday I bought 2 boxes of refills in preparation for a trip I am taking. I tested all of them to make sure they work so I will have enough to last through my journey. 2 of the 4 refills are bad. A friend of mine gave up on Blu for this reason, so I know Blu must have many customers with the same complaint. Except for this problem I like Blu for its lower nicotine levels and its shape. However, this problem is driving me away from Blu.