What's a good way to teach a dog to do blind retrieves? He's a year old, he'll swim/run out for ducks and dummies if he sees them, but he's having a hard time just going on the retrieve command if he doesn't see something out there. How do you teach that? Is it a trust issue that is developed another way or is there a technique that specifically teaches them to go when told and to keep going until they find the bird or are called back? Thanks.