A line FileMaker line chart is not a cartesian graph as illustrated by your chart. I don't know of a way for a FileMaker chart to show the data the way that you want.
Well its half cartesian I suppose... the Y-axis appears to scale based on the data values but the x-axis appears to place the data points equally along the axis regardless of data values. Kinda odd-- the point of line charts is to usually to graphically indicate slopes, trends, changes but if the x axis isn't tied to the data these trends will always be distorted or hidden. Whats the point of drawing a line between points if the slope of that line is meaningless? One idea I had was to use a scatter chart and generate additional data points that would (mathematically) exist between the two points I want a line between-- generate enough points and it starts to look like a line.
Yes but the X axis does not show a scale. This type of line chart is more like bar chart or histogram but with a line drawn from top to top of each bar and then rwith the bars removed...
This type of line chart was never intended for the purpose to which you want to apply it.