You may want to try something smaller like a toothpick or something like a straw. Another thing to do is to "shape" him to target the stick. Determine at what range he gets uncomfortable with the target stick, then start by placing the target stick outside of that distance (ex. if he gets uncomfortable when it's 1 foot away place it 1 1/2 feet away from him) and click him for just looking at it. Once he seems okay with that, move it a little closer. Repeat until you are able to work with the stick close to him then switch from clicking for him looking at it to moving toward and eventually touching it. If at anytime he seems uncomfortable, move back to the previous step and work a little longer.
From reading about shaping it might seem like it could take forever, but they usually get so into the game they forget they are afraid of the object and you find you can move faster.
I love shaping and breaking behaviors down into small steps. It takes some patience but I love watching when they finally get what you are trying to train them to do.
