You may be looking at the 1040 amount due. When you file an amendment, whatever was corrected, will show on 1040 the corrected amount that should have been owed on the original tax return. This isn't an "additional" amount owed.
To see the amount you owe or refunded after the amendment has been filed, look at Form 1040-X Line 20 (if balance due) or Line 22 (if refund due). I'm assuming that since you added a business expense, you should have a refund due and would show on Line 22.
