How to Show null values in Report Output

Hi Friends ,

                  We have a Requirement in Bex . Query have  a keyfigure with Zero's, Null values. In query output have to hide Zero's and need to show null values.

The below is the example

Material      Quantity                       

   A                0

   B                0

  C                     

   D             

   E                20

   F                50       C and D having null values . it should be display in Output.             

Out put should be

Material      Quantity                       

   C                     

   D             

   E                20

   F                50

Please  Advice how to Achieve this.