nvd3 scatter chart circle size not working

[majeti dinesh]

I am trying to change the size of the circles in the scatter plot. I use the attribute size but even if I change it to 10, 100 etc, the size of the circles is not increasing. I tried using .sizeRange([minArea, maxArea]) and the maximum size increases. I am unable to understand how the size effects the perceptible sizes. Is it relative size?