Timber's right on this one. Make sure you bait is fresh and cooked. Some people will put out a dead fish and wonder "why they ain't catchin". Coons are more finiky than possums. Also drippin's from your outside grill will work well.
You'll be hard pressed to kill them during the daylite unles you can find their den tree. Even then, they might not come out til to dark to see.

Good Luck. Capt Brad.