it always make a balls up when you automatically plot a chart.

on the first page of the chart wizard, select chart type as xy scatter, then it don't matter if the x-axis isn't in equal increments

2nd page, select the 2nd page tab called 'series'. delete the series that it's put in as bollox, and enter them manually. it's self explanatory from here, with te line name, x-axis values and y-axis values

that should sort it for you