Multiply Table/DataSet Value by a What-If Value

Very new to Power BI, so I'm certain the anwer will be of an embarassingly syntactical nature,

I'm extracting Fields/Columns from an MS-Access Database.

One of these Columns is [Client Commission] = the $ revenue from an individual payment received.

Another Column is [Manager Commission] = the $ paid to a Mgr from an individual payment.

Say that a payment/row = $200 and the Mgr received a commissin = $50

The Database is already calculating [Client Commission] - [Manager Commission] = [Gross Profit]

So it's not necessary to create a calculated column for that in Power BI.

However, I'd like to use a What-If so that the I can create another column = to [Manager Commission] but that can be can be moved up and down based upon the selected value in the created What-If.

The What-If is set up to run from 0.75 to 1.25 giving the option to reduce [Manager Commission] to 75% of the actual $ amount, or increase it to 1.25% of the actual dollar amount.

I can't seem to find the correct syntax to multiply

CheckFromHistory[Manager Commission] * Mgr Change[Mgr Chg Value]

(CheckFromHistory being an actual table and Mgr Change being the table created by the What-If)

I can successfully multipy columns within the individual tables, but not across the two tables.

There is NO relationshop between the CheckFromHistory table and the What-If Table Mgr Change.

Can that be the problem ?  Or is it, as I suspect, a simple syntax error on my part ?

Thanking you in advance,