You may have inadvertently taught your dog to ignore you. When you repeat a command over and over again your dog will soon tune out what you are saying and begin to ignore you. This is because dogs language is through body language.
A young Staffordshire Bull Terrier getting some training in the park
When training your dog you should never repeat a command more than 4 times. Your dog may have also learnt to ignore you because he associates your command with a negative experience so will ignore that command.