Cannot build vertical stacked bar chart! HELP!

I have a simple stacked bar chart I want to build with month/year across the bottom that shows the number of orders by category (A,B,C and D). I understand that I must have 2 dimensions and 1 measure. However, the chart is not counting the number of orders by category correctly. I cannot find anything on the net about how to create a vertical chart and troubleshooting why it won't work.

Here's an Excel Pivot of the data:

Year/tmonth A B C D

2009/12 1 1

2010/02 1 1 2

2010/04 1 1

2010/06 1 1

2010/07 2 1 3

Grand Total 2 1 4 1 8