In Excel 2002, Column "A" data: 6, 7 8, 9, 10. Column "B" data: 200, 300,
400, 500

When I try to create a line chart, Column "B" data is in the X axis. I want
Column "A" data on the X axis, so I swap the two columns. No matter, the
chart still puts 200, 300, etc. on the X axis!

How do I choose which column is X, and which is Y?