Psychologists state that all human beings have two primal fears hard wired into them naturally: Fear of loud noises, and fear of falling.
Break falls are psychological. Most students can physically do them. It is mentally where they usually come up short. If you have some softer mats around, try letting your student use those. Let them see that nothing bad will happen to them when they fall. Their mind must believe they can do it, or else they will panic and pull out of them, at which point they will usually hurt themselves.
Try looking at ukemi from other martial arts as well. For instance I have heard that Bujinkan have some very soft break falls for beginners. Try and find a breakfall they can do, and let them do that. Once they realize they can do some sort of breakfall, the rest will follow.
P.S. TruWarrior53 (and judging by your post here that seems the most inappropriate name in the history of internet forums), you shouldn't be allowed to teach, if that could even be called teaching.
"Let your food be your medicine, and your medicine be your food"