Scatter Chart Horizontal Labels

I am using Excel 2010.
I am attempting to create a Scatter chart using data similar to the following...

Carriers Revenue
A 100
B 125
C 200
D 150
E 145

On the scatter Chart the Horizontal Axis Labels display the numbers 1, 2, 3, 4 and 5 and not the alpha characters A through E. I would like the alpha characters A through E to display. I have right clicked the chart, Select Data, and the Horizontal (Category) Axis Labels display the correct values (A-E), but the "Edit" box is greyed out. If I use a line chart the Horizontal Axis Labels are correctly displayed.

How can I get Excel to automatically label the Horizontal Axis in the format I wish?

I have found that by editing the horizontal axis title you can create your own x-axis labels.

Instead of labeling the horizontal axis as "Carriers" (or what have you) you would label it as "A B C D E" with the appropriate amount of space in between letters to line them up with your data points.

More of a kludge than a solution, but I hope it helps.