Key figure calculation problem.

Hi,

Can any one help me?. I have two keyfigures as Quantity and Amount and sliced by Cost element. For all cost elements I have amounts but only one cost element has value for Quantity. However, I want to have new keyfigure as per/unit by dividing by the same quantity for all amounts. For example,

Cost Element Quantity Amount Per/unit

A 200 1000 5

B 0 2000 10

C 0 1200 6

I used the formula variable 'SUMGT' and it helped but it is not helping with other conditions.

Thanks

Sundar