You might also use tongs or tweezers to pinch-damage the nose a little right before offering...that too will release a bit more scent.
Some snakes just didn't get the "talk" (or the manual) lol*....and practice (eating) helps. Some snakes actually have to spit it out & start over. I've also seen
some snakes with wider heads that just fold the rodent in the middle & down it goes anyway!(show-off rattlesnakes, lol...)
*Btw, this shows you how little they use their vision & that not much logic is involved either.