
By the sounds of it you still don't quite have that bond with your boy yet if you've only had him 4 weeks and until then his been with the breeder.
I suggest you do some "bond building" with him. Lots of one to one fun time, get out to training clubs (ringcraft and/or obedienc).
He knows what to do but at a guess you two just don't yet "click" I've had this with dogs before which I handle but they connect immediently with my brother. I normally win them round by spending time one to one which is fun and not always ringcraft. :) Also when training to stand and move make it really fun at the end. I will sometomes stop part way though and just start playing with the dog, really picks them up and don't really have dogs "not show" for me unless they are in a stubborn mood! :-D then there's just nothing to do!