Why Does My Refrigerator Freezer Not Freeze Ice Cream?

If is is a frost free, it constantly thaws slightly and melts the ice and thus the ice cream
if it is not a frost free it may have too much ice build up to be running at the proper temperature
if there is not an ice build up, your freezer may simply not be set cold enough
I set the temperature of my freezer to my ice cream - solid but not rock solid

Better check your ice box setting