Hi Rev,
Did you run Calculate? Api.Data.Calculate only runs on calculation or consolidation.
Did you set your account with a Formula Pass later than the one assigned to Salary? Calculate will only run if a formula type is set to a Pass, and it will follow the sequence defined by passes.
Are you sure the original value is stored? If it's dynamically calculated (i.e. the account is marked as Formula Type DynamicCalc, or it's just a calculated column on the CubeView), then you won't be able to use api.Data.Calculate at all; you can look at the Design and Reference Guide in page "Writing Formulas" under the section "Writing Dynamic Calculations".