The Microsoft Access Database Engine does not recognize...

Ah! It is a crosstab query. You need to declare the parameter explicitly. You can do this in two ways:

1. Open the query in design view.
Click Parameters in the Show/Hide section of the Design tab of the ribbon.
Enter [Forms]![Inventory Reports]![SupplierName] in the Parameter column and Text in the Data Type column, then click OK.

- or -

2. Insert the following line at the top in SQL view (this line must come before the existing SQL string):

PARAMETERS [Forms]![Inventory Reports]![SupplierName] Text (255);