Very rarely do dogs not respond because they didn't hear us. If your dog is unresponsive, it could be because:
He is too excited/distracted
He has not yet learned the cue in that specific situation
He has not yet learned the cue well enough in general
He is stressed or nervous
There are too many competing reinforcers
He is tired or over-trained
Instead of keeping on repeating the cue over and over, change some of the above factors and try again (or stop and try again the next day).
