In a trial a dog that doesn't do the bark & hold will lose points the point of the bark is to let the handler know where the bad guy is for capture in a real situation and let the bad guy know that if he tries anything the dog would bite. The best way to teach the barking is to tie the dog to something and frustrate the dog into barking for the bite you can do it yourself with a flirt pole or rag just tease the dog with the rag until they bark or make a noise then reward with the bite this may take some time but should work.