wannabemedic

I am a student in ontario Canada, I'm having difficulties with my preceptor. I find he is giving me an extremely hard time. He seems disappointed having me as his student. My first day with him he didn't make eye contact with me or really acknowledged my presence. He has only ever given me negative feedback. When I do well at something he says nothing, when I screw up on something small he jumps on my back. He's quick to give orders, and never cracks a smile to me ever. Never asks me anything personal or seems to have any interest in my presence at all. We had a hot call, and when we finally had the patient in the back of the truck, he snapped at me, demanding where something was in the bag...he said "you stocked the bags, Where is it?" I looked down and it was on his foot. When I picked it up and handed it to him, he never apologized or even said thanks. I don't mind working hard, or even picking up his dirty work. Why the attitude? I don't get it????? Am I missing something obvious??? Why are some preceptors like this??? Please would someone fill me in.