Fear of training?

Maybe he associates training time with pain because of his previous battle with Pano.

What kind of training do you use? How are you trying to teach him "come"? What kind of treats is he getting, and where do you do your training sessions?

Hi Welcome, we do need pictures. Just a thought he may not be understanding you, and is getting nervous as to what he needs to do. Maybe go slower w/ him.

What training methods are you using?  Maybe he's just a very sensitive dog and you freaked him out or scared him if you said "no!" too loudly or used a harsh tone or a leash correction.  (By accident, I mean -- I know you weren't trying to scare him.  But some dogs just are very sensitive to correction.) 
 
You might give him a fresh start with clicker training if you haven't tried that already -- it's all positive and there aren't any corrections you need to make.  Dogs who shut down during old-fashioned types of training often do really well with the clicker.  You can check out the clicker training forum here for more information.
 
And he's a cutie! 

I second trying out clicker training.
Have you ever told him no, or at or something like that when training?  I've noticed that with my beagle, if I say att to her, she'll kind of shut down.  She has never been beaten or anything, she's just sensitive.  If you have, quit.  Also, try out better treats.  There's a recipe section here that has some great treats in it.  My girls went crazy over the liver treats.

Sometimes a structured training session can be a bit intimidating to certain dogs.

I would pay attention to your own demeanor and try not to to be too intense. It's not a switch it "on" or "off" and we are now in "training" mode. If your demeanor changes during the session, your dog may not understand and "read" you as being in an "alert to danger" or a "you asserting dominance and wanting submission" mode.
 
I just personally believe dogs react to their social group member's behavior first, and are relaxed and receptive to instruction, second.
 
Dogs pick up on our subtle cues and often "react" to us, rather than taking intruction in a more comfortable matter-of-fact-way. Your facial expressions, vocal pitch, and body language is what a dog cues to first, IMO.

I think you may need to work on your interactions in order to keep your dog at ease.

Just try casually incorporating some training using positive reinforcement (check out our clicker training section!) and relax a bit (no big deal man). [] 

Another suggestion... to make it a little less intimidating to him.. always keep treats on your person and when you catch him do something like.. coming to you.. tell him good boy good "here" "come" whatever you use for a command give him a treat.  If he comes over and sits down next to you tell him "good sit" and give him a treat.  Eventually he'll associate the command with the action and do it whenever you tell him to. 

skip the whole idea of "training time" and make "training time" be "all the time". Keep treats on you and all over the house, and at random moments practice something. Make it a fun game.

Thank you, everyone, for responding.  I appreciate all the input and suggestions…it all makes so much sense.  I was missing a lot of “clues” by being so close to the situation and worrying so much about Tucker.
 
To answer some of the questions about how Tucker and I train, we work alone in my kitchen, which is quite large (when the weather is better we#%92ll work out in the yard). 
 
I use different treats like Cheerios, or pieces of his food or cheese cubes.
 
The Puppy Kindergarten class that we were in used the clicker training method and it was chaos…all those clickers going off all over the place…it was SO confusing and Tucker seemed to really just give up.  They also did a “pass the puppy” exercise, where each person held all the other dogs to socialize them, which is a FANTASTIC exercise…but Tucker HATES being held and always has…he#%92s very social, very sweet and loves people…as long as they are not holding him.  I#%92m thinking he#%92s going to need a one on one training situation rather than a class…he does seem VERY sensitive to confusion and noise.  I am very open to trying the clicker technique with him…just not in a crowded class.  I#%92m going to pop over to that board and do some reading.
 
Thank you all again SO MUCH!!!  You#%92ve given me some great ideas and some things to think about and digest when working with Tucker.  He#%92s a sweet boy and is very eager to please…I know we#%92ll be able to work through this.
 
Donna

he sounds like he might be a "perfectionist"-- worried about getting it wrong even though he's never been "corrected". One of my dogs is like that. Incorporating training seamlessly into games and doing "free shaping", where the dog is basically rewarded for doing anything, really helped her get over her self-imposed "fear of getting it wrong". You may also be subconsciously stressing your dog by your attitude, if you approach training in the mindset that you "have to get this dog trained", instead of "let's have fun together".   How about toys-- will the dog play with you as a reward? good way to build drive and enthusiasm for training.