Yeah, what
@Eskie said. Either try a different tank/coil/topper on the mod to see if it will fire, or try the same coil on another mod.
You can also throw it on a multimeter if you have one. If it reads correctly on there you know it's not a faulty coil.
Pretty silly but it bears mentioning: make sure you have selected "new coil" on the AL85 after putting the new one on there.
I wouldn't be that shocked if there's something wrong with the coil versus the tank only insofar as pre-made coils that come with toppers aren't usually the greatest, but I could be way off base.