It's definitely sounding like a connection issue of some sort. Make sure your coil is installed correctly, with the threading as normal and also don't overtighten the mod/tank which sometimes happens when trying to fix a connector issue.
I would inspect your tank threads closely. Are they all neatly in line as they should be, with no misshapen threads? It's possible that your connection is gunky as well, sometimes gently cleaning the mod's 510 connector with a q-tip to make sure no juice got inside it can help, as well as cleaning off the threads to your tank.
If you have the option of trying to put the tank on another mod to see if it reads, that might help isolate what may be going on. You could also go to a B&M vape store to see if an employee can help isolate the issue.... I've had that happen with one tank since I started vaping this time, but I broke it when I dropped it and that tank was pretty much toast. You can get replacement 510 pins but I'm not entirely sure what is going on with yours. Do you have a vaping pal that might be able to help? Sometimes these "new" things can get aggravating....
Also, if all else fails, how elderly is your equipment and where did you get it? You may be able to warranty it if you can't figure out the problem.
Sorry to not be of more help, I hope you are able to get it figured out.
Anna
