I echo the recommendations put forth by Jmonte35. Force fetch conditioning would likely solve your problem and create a more solidified starting point for more advanced work to come. You might also consider standing along a long straight fence, face one way with the dog and throw a short bumper of say 10-20 yards while he marks that bumper as a memory bird, turn the dog and yourself 180 degrees and toss the second go bird,mletting him mark that fall. Send him on the go bird, once he delivers to hand, send him on the memory bird and give him lots of encouragement when he nears that bumper. Hopefully he gets motivated enough to pick it up and deliver. (The fence is really optional and only important if he is not taking a straight line). If thia does not work, I would surely make a point of FF conditioning him before working any further unsuccessful doubles. train with planned success as an objective.
Good luck with it.