How is your basic obediance? Is your dog solid when it comes to heal, sit , stay and come? Try using a check cord to remind him to stay and work on it daily...try it in the house first, all my training starts in the house, when they aresolid there then move to the yard. If your dog is solid on obediance and I mean solid then he should mind you at all times regaurdless of how close he is in proximity. If not, take a few steps back and get him solid on stay...it takes time but it is worth every minute you will spend.
I practice with a stay rug in the house, the dogs are not allowed to wander around. If they are told to "get on your rug" they know not to move unless released. The release is just as important as the stay, if you don't release your dog from a stay they get bored and will break, if they know a release is coming they will wait it out no matter how long you ask them to stay. Don't forget to give alot of praise and an enticing reward to start with...I use the fat from a ham hock when I first teach this it really gets the attention of the dog, reward when he does what you ask of him & don't be afraid to get silly and love up on him, they respond best to happy praise. Keep your corrections quick and sharp, don't dwell on the mistakes or breaks, repeation is the key...keep your anger in check and repeat until he understands.