walkingmy dog

Question
 Ok heres our story.I have a half american bulldog and half
bermesse mastiff.Smart,smart,smart.Stubern,stubern.I have been working with him all most every minute he's awake.I am a disabled vet,I live in a 11th floor medium size apartment.
He has learned where to sit and ride in the elevator both
ways.I say potty training 90% complete,he fetches like a champ,we are working on get and drop as well as heal and a few other lessons here or there.Now walking first off I am in a wheelchair for the rest of my days,so HuuWee is going to be my aid/companion dog.I have had HuuWee for two weeks today.He had his problems walking with me but I also have a better half in my life and now all of the sudden he is
stubern.He will walk fine for four or feet then plant his ass and refuse to move for her,I actually had to go get them on the other side of the street yesterday.Now he is doing it with me,we have done eveything from collor to harness to leader.Yes the leader makes things awhole lot easier but he cant walk me I have to walk him.He will be 14 weeks old tomarrow,I have to relearn him not olny that both mommy an daddy are alfa not just daddy and he's got to get this walking thing down.We dont start school until late next week and my body cant handle his stuborn stoping every four or five feet,leading to my four or five small tugs on his leader.I call him I praise him,Ive tried treats of many a kind He is stubern as a mule,Please help me turn
my dog into the future aid dog he;s supposed to be,what am I supposed to be doing that I am not.Or what Im doing that I should not be doing...

Answer
Many puppies balk on the leash, and the fact that you have been able to get him to walk is good.  But, pups don't generalize well either, so they need, at this stage, to be walked by all the humans who will deal with them on a regular basis.  Tell his mommy to entice him by slapping her leg, using a high pitched voice or a squeaky voice to get his attention, and lure him with a treat to walk along (something good, not just a milk bone).  
If this is to be a service dog for you, you may want to think about clicker training.  It's useful for teaching basic and complex tasks.  Free lessons here: www.clickerlessons.com.  Then, you should look into getting Barbara Handelman's DVD's on training your own assistance dog.  Pricey, but well worth it. http://www.dogwise.com/ItemDetails.cfm?ID=DTH203