When I looked at the code I wrote for an example, I realized that I also failed to comprehend how to decode the X axis. I ended up creating a normally hidden scale that I manually set. Obviously there is a way to do it, and I don't know what it then (2008) and now.
It was difficult to set the scale up the first time, but where the software was used, the same data was collected over and over again, so the scale rarely changed.
Good Luck.
