Shake and Rattle... no Roll.

My baby refuses to roll over. It's aggravating. She's six months old. It's not that she can't... I've seen it. I lay her down, leave the room, she gets upset and starts screaming at the top of her lungs. If I'm gone long enough, she'll get mad enough that (I'm guessing) she thinks to herself, "I'm getting out of this place!" and proceeds to start to roll. She makes it onto her side then gets more frustrated at what I can only assume is the fact that she has to go through all this in the first place, and just gives up. But she won't roll! I'm not concerned about her developmentally, I mean she is right there with her peers on everything else and even more advanced in some areas. But the lack of rolling is... argh. I'm at a loss. She has tummy time every day. She hates it. It's like, by refusing to roll, she's rebelling against the establishment that says she has to spend time on her tummy every day. When I put her on her tummy, I can't help but laugh as she lays there in the "front leaning rest" position, and looks up at me, as if saying, "Why are you submitting me to such torture?" I can't help but smile and yet, wonder. Why does she hate it so much? Will my baby be one of those children that goes from 0 to 60 in no time? Will she all of a sudden one day just get up and take off walking? Because without the whole rolling thing, I don't have much hope for the crawling thing either. I think she's too impatient for that. :) But I guess we'll have to see. In the meantime, I'll have to hold my tongue and try my hardest not to hate those mothers whose babies are merrily rolling away.