Why doesn't the total of Sales by Category match the revenue on Sales by Date?

The two reports measure different things:

• Sales by Date (and Sales by Location) add up order totals: the full amount of each order, including shipping.
• Sales by Category (and Sales by Product) add up product line amounts: what each product sold for. Shipping is not part of any product line, so it never appears there.

So the category total is usually lower than the date total for the same period. Items on an order that are not linked to a catalogue product are also left out of the product and category reports.

For matching figures, compare reports of the same kind: Sales by Date with Sales by Location, or Sales by Product with Sales by Category.