I inspected all my hives today and found one very very weak colony. I knew they wernt in the best of shape going into winter but i though they could make it through, plenty of food just low numbers. There is only about 2 or 3 med frames of bees that makes up their cluster so i put a double screen on top of a stronger hive in hopes of heating the weaker colony. I did this and now there seems to be a lot of action at there small entrance that the double screen provides for them is this robbing? Did i do the correct thing by placing a double screen between a stong hive and setting the weak colony on top?