He is a very nice looking dog!
When we got Rusty (from our neighbors) he had never been around other dogs, other than his litter mates. He would constantly bark at first, but once he learned that if he stopped and watched, he too could play fetch or run with the other dogs...he has come a long way...still working on somethings, but he has proven to be a very smart dog!
Give it time...I am sure he will come around!