I have been trying very hard for several weeks to tame my 10 year old male Cockatiel. Every time I go near him with my hand he hisses and tried to bite me. He was in a home that did not give him attention and he was left alone in a room most days by himself. I want to try really hard to get him to trust me. I open the door of his cage and he comes out and he will sit on his cage right next to me. But wont let me touch him. Please Help!