Summing All in Powerpivot

[DRKNOW]

Hi,
I have created a power pivot table as shown in the picture. I want to calculate quarter over quarter sales change. For which I have to divide for example corporate family "Acer" 's sales in 2012Q4 by sum of all the corporate family. I am using measure to do this. But I am not sure what formula I can use.

My need is to create two columns, one for 2012Q4 % and one for 2013Q1 %. Then I will another column to find the difference. So the formula for 2012Q4 should be like this 1624442/(1624442+22449+1200+16123) . Any idea which function can help me do it?

 

[powerpivotpro]

Try a measure like:

SUM(Sales[Amt]) / CALCULATE(SUM(Sales[Amt]), ALL(Sales[Corporate Family]))