Here is my statement. I am using the design view for making queries because I'm still very new to all this and I can't grasp the SQL view yet. So here it is:
Code:
Tax: IIf([Customers].[State/Province]="MI" And [Products].[Taxable]="Yes",CCur([Quantity]*[Unit Price]*(1-[Discount]))*0.06,0)
Tax is an expr that is trying to be calculated.

Here is my error:

The SQL statement could not be executed...