Lesson learned

[model 70]

well i'm new to trapping so my traps are very limited. I set out the old cage trap and that little #110 coni i have.my folks have been seeing a oppusom around their place that's be acting "funny". so with the #110 i dug a hole in the ground about 3"x4" around and about 5" deepand set the trap over it. then i dug a slot for the single spring to set in so the whole trap was damn near as flat to the ground as i could make it. then i ran an 18" stake through the little ring on the chain that comes attached to the trap. then in the hole i dropped some peeled bananas and some table scraps(meat). this morning i found the opposum with the trap around it's neck about 40-50 feet away still very much alive. a couple shots with the .22CB's and it was dead.

my question is, how do i keep the animal from pulling the chain up off the top of the stake if the trap fails to kill it?.