Create Calculated field to store value under certain condition

Hi friends,

I want to have two measures to store value under two mutual excluded conditions:

-[Scenario] -Plan

-[Scenario] -Actual

and then to do some further analysis using the difference (Actual-Plan) among different countries

My current code is for Actual is:

IF [Scenario1] = "Actual"

THEN [Total Amount ]

END

The problem is I cant get the difference since these two scenario cannot hold at the same time, which means the row which has Plan value would show 'null' for actual value.

Is there any way I can get my 'plan' and 'actual' values in order to get the difference?

Thanks all!!!

Loretta