From TNR Works

WHAT TO DO IF THE CAT WON'T GO IN THE TRAP

Vary the way that you are covering the trap. Some cats prefer to be covered, but some will only go in if they can see out the far end. Other cats prefer to be uncovered, but you'll want to be nearby to cover the trap quickly to calm the trapped cat. The uncovered trap should be a last resort to catch the last cat of the colony.

Try using different bait. If possible, heating the bait will increase the aroma and attract the cat.

Trapping within the same colony, try to use the same base and cover as used on previous cats, provided they're not soiled. When using fresh bases and covers, prior to putting them in the trap, rub them through the dirt in the area to make it smell familiar.

Trapping in a new colony, rinsing down the trap with extremely HOT water 30:1 bleach dilution to disinfect, rinse thoroughly. Since you can't over rinse, please be thorough as to avoid an overwhelming odor to the cats senses and possibly cause nausea. When using fresh bases and covers, prior to putting them in the trap, rub them through the dirt in the area to make it smell familiar.

The size of a trap is very important. The larger the cat, the larger the trap. Also cats can be claustrophobic and will be more apt to go in a larger trap and some just don't care, they want the food.

IF, AND ONLY IF, you are trapping in a secure area (your own backyard, inside a building, etc.), you can rig the trap to have both ends open for a few days with the food in the center of the trap. On the day of trapping, simply set as required for trapping.

If you're going after one specific cat and others are entering, prop the door open with a stick and a string attached to pull when the right cat is in. Just make sure the cat is far enough in for the door to close.

If you're fortunate to have two traps. Open and secure the non-setting doors and secure the traps together. Open both setting doors and secure for daily feeding inside. On day of trapping, set doors as usual, leaving non-setting doors open while non-setting doors are still open and both traps securely attached to each other.

If these tips fail, as a last resort you may want to try a drop trap.

Not recommend until you are down to your last 2-3 cats that refuse to enter a trap. Be sure trap is on flat ground, any little hole for the snout to go under will be used to escape. AND PLEASE, wait patiently for cat to be fully inside to prevent a hurt appendage and immediately cover trap, not only to prevent escaping, but to calm cat.

When transferring cat, keep drop trap covered, attach covered transfer cage/trap to drop trap and line up with door, open up both guillotine type doors, allowing cat to enter trap. You may need to uncover far end of trap, as the cat may see this an escape to enter. Never uncover the drop trap fully. You want the least amount of anxiety as possible.

Why not use drop trap from the beginning? Much like regular traps, if cats are watching and see the trapping experience, they’ll avoid the traps, making it harder to catch the remaining few. Cats are EXTREMELY smart.