Scatter plot in Access

I am trying to produce a scatter plot in Access. I am using the ‘Insert chart’ tool in Design, and even when I choose the column that has the figures I want for the X-axis, these are not being plotted. Instead, the plot is taking these values as the series, and the X-axis is numbered as 1, 2, 3 …. Is there a way to specify which column contains the X-axis values so that I can get my Y vs. X. My X-axis values are not evenly distributed.

The Y values are coming out OK. My database is Access 2007.

Thanks