SKF in CJ20n: Not able to plan quantity period wise

Hi All,

I want to plan SKF at activity level in CJ20n in Stat. Key Fig. tab. for period wise as you can see in below screen shot

However i am not able to see period wise plan of SKF option here (for example i want to plan for Aug Sept and october each with different quantities eg. 10, 40 , and 50)

If i run S_ALR_87013548 transaction to see my plan SKF i can see the compete 100 divided equally in month of august to October which is my start and finish date for this activity.

How can i change these quantities to 10, 40 and 50

Regards

RAJIV