Maybe the carto isn't making a connection with your battery. Put something very small (unbent paper clip) and pull the end out on your carto slightly. See if that helps. If not, it might be dead. But it could be the carto not making a connection with your battery.
You could also do the same thing to your battery, pull the center pin out slightly. But you really have to be careful doing this- I'd do it to the carto first.