proportional key figure in snp is not correct

Dear SAP Expert,

I've created a key figure name " co cau mong muon" in snp planning book to calculate key figure "so luong dieu hoa" in macro like this:

"so luong dieu hoa" = "ton kho ke hoach" * "co cau mong muon"

but the system considered value of "co cau mong muon" as number format not proportional. so the result is not correct. for example:

"so luong dieu hoa" = 1000*(30%)= 30000 not 300.

please help us.

thanks so much

hungth