my puppy won't walk...

Hi all,

I have a strange issue with my puppy. My gf and I got him in early december. He's now about 4.5 months old, doing very well in all aspects except this one... he doesn't seem to like going for walks.

When we try to take him out, he'll go maybe 20 feet, then just put on the brakes. We can coax him to get started again, but it's the same thing... another 20 feet or so and sudden stop.

He obviously wants to go outside (sitting by the door and whining even when he's just been out to "potty"), he's healthy and energetic, but this strange behavior. We've tried coaxing him with treats, toys, praise, etc; but nothing seems to help. It's getting kind of frustrating.

Other than this he is taking to tricks and training very well. I've been lurking here for a while and thought it was time to sign up and see if the good people here can offer some insight.

Thanks in advance!

Jamie

edit: forgot the basics..

he's a mixed breed rescue (we just sent out the dna test today to find out what breed(s) he is... some kind of terrier. 4.5 months, not yet neutered. at the vet regularly so we know he's healthy.