Calculated Key Figures - Result row sum is wrong

Question

Hello all,
Using the example below, I built a calculated key figure for TotalPrice (material amount * material price per unit).  I set TotalPrice to calculate the result as a "total".
OrderID OrderLineID MaterialID Quantity PricePerUnit    TotalPrice
1                 1                1            1              5.00           5.00
1                 2                2            1              3.00           3.00          
2                 3                1            2              5.00          10.00
2                 4                2            1              3.00           3.00
3                 5                2            3              3.00           6.00
ResultRow:   -                 -            7            19.00          27.00        
Now, if I remove OrderLineID and MaterialID drilldown (or from the query rows), I get the following (wrong) results for TotalPrice:
OrderID Quantity PricePerUnit TotalPrice
1                 2              8.00         16.00*
2                 3              8.00         24.00*           
3                 3              3.00           9.00*                   
ResultRow:  8             19.00         39.00* 
- wrong results
Is it possible to be able to remove the orderlineid and materialid fields from the query rows and still get correct results for TotalPrice?
Thanks!
-B

Answer 1

I solved the problem by adding an Exception Aggregation to the TotalPrice calculated Key Figure. 
To be more specific, I added an Exception Aggregation (set it as type "Total"), then set the reference characteristic to OrderLineID.
As a result, the exception aggregation takes into consideration the orderlineID row when calculating the total price (quantity * priceperunit).  Therefore if you place the orderlineid in the free characteristics instead of the query row, the calculation is still performed correctly.