I agree with most of the above, with the exception of "braining". I've actually never heard of this actually working in the 20 years or so I've been around this hobby.
Make sure you're getting the prey good and warm. Use your temp gun to make sure it's heated up to approx 100°. Keep in mind smaller prey cold quickly so you may have to reheat and offer more than once.
Wait at least 5 days to offer again.