Finding volume of a function rotating around the x-axis

Find the volume of the solid formed by rotating the region inside the first quadrant enclosed by http://math.webwork.rochester.edu:80...4d33750161.png and http://math.webwork.rochester.edu:80...da352895f1.png about the http://math.webwork.rochester.edu:80...dd0b8b8e91.png-axis.

So I know it is pi[ outer^2-inner^2]

the boundaries are 0 to 2. and I know that y=8x is on top.

But I can't seem to get the right answer, I would get a negative number...