A question about the pre-flop calculator

[heath_bar1]

I am working out some probabilities by hand and comparing them to the pre-flop calculator. I was hoping someone could tell me what I'm doing wrong on this one.
If you have pocket aces what is the chance of getting 3-of-a-kind on the flop?
I have 2/50+2/49+2/48 - 3/1225 - 12/1225 = 463/4200 = .1102

3/1225 is the chance of getting 4 of a kind.
12/1225 is the chance fo getting a full house.

According to this site it should be .1078.

If I subtract by 3/1225 again I get the correct number.

Hopefully someone can follow my logic and tell me what I'm doing wrong.

[heath_bar1]

I'm replying to my own post.
I still don't know why my other method didn't work, but I found an easier way to look at it.
I multiplied the chance of catching either ace times catching anything but the final ace times the 3rd card being neither an ace nor matching my second card. Then you must multiply by 3 for the variations of the order.

2/50 x 48/49 x 44/48 x 3 = 132/1225 = .1078

I guess I just tried to get too fancy with my first effort.