The first MVP V2 I bought had the same issue. Some devices would work, some wouldn't, including the iClear 30 that came with the kit. Pulling the pin on the topper sometimes worked, but if I took the device off and immediately replaced it, the MVP wouldn't fire. And, yes, all the devices fired on my Spinner. It was all very frustrating. However....I bought another MVP V2 recently from 101Vape and it has been firing and working consistently...except for the iClear 30 that came with it! I don't care, tho....I'm much more a carto tank vaper than anything else. So, the upshot is that there may be an issue with the center pin on the MVP V2 being too low (most likely) for some toppers to make good contact. After trying many things, my solution was to buy another MVP V2 (I do love the little thing!) and, voila!, problem solved!