I presume you are selecting the data and then inserting a chart. For some reason that I have not been able to figure out, sometimes Excel doesn't interpret the leftmost column of data as the x-axis labels. More often than not, it interprets it as another data series and the default x-axis labels are an integer series (i.e. 1,2,3,...). This is what I found to be the case in the example from your original post.

To fix this, you have to:
* delete remove the series that should be the x-axis labels from the Legend Entries
* edit the Horizontal Axis Labels so that it uses the range you want.

I haven't tried Peco's workaround yet, but that may be a shortcut. Of course, like mine, it is just that...a workaround. It would be nice if we could find out how to set Excel to do this automatically. It seems that it should, at least from my viewpoint, since this is the way I always make charts. How many times do you make charts that simply use an integer series axis?