[yorkietalkjilly]

He's no doubt uncertain about the outside or the leash, his collar or harness and you probably need to try to keep his walking sessions very, very short to start with so he isn't overwhelmed by whatever is worrying him. You could try the things below in very short sessions of say three to five minutes and then bring him back inside, play vigorously with him and toss his ball for him, to work out his tensions from doing something he's not very pleased with right now.

You could try bouncing his ball out in front of him, squeaking his favorite squeaky toy at ahead of him, tossing it forward on the ground, to encourage him to walk forward or take some warm, boiled chicken in a treat pouch and hold a piece in your fist out ahead of him to get him taking steps forward on the leash and getting him focusing on that. A lot of dogs won't walk outside because of scents, sounds or strange things they aren't used to looming here and there or the other dogs in the area they can smell and all the energy and excitement of being outside just shuts them down. It's different out there and they know it.

Other dogs won't walk because they don't like being on the leash but usually if you can just get them to take a few steps to go after a toy or toss a treat ahead even on the ground and let them go to it and get it, as you say "Good dog" and encourage them, they will get the idea that walking isn't that bad.

Putting him on the leash and letting him walk around on it will get him used to it little by little. See if you can lead him around on it inside the house and if so, in a matter of time, short sessions outside will start to come more naturally to him.

Putting him on a long leash that you lay on the ground with the hand loop under your food as you place the dog say 6 or 8 feet in front of you and backing away to the 6 or 8 foot distance, then encouraging him to walk toward you can get him started forward also. If he does it, just keep moving away from him another time or two and that's enough for the first few sessions. Praise him lavishly in a squeaky little voice anytime he does walk forward on the leash. Eventually you can then raise the leash up as he walks toward you and one time, just start walking beside him for a bit.

You might try those things and see if they will get him going. If not, take a break until he's a little older or more settled in with you and retry the training.