I have the following as an example set of data points to be plotted on either
a line or scatter chart (doesn't matter which as I am having the same problem
with both!)

X Y1 Y2
1 2 1.8
2 4
3 6 4.5
4 8
5 10 9
6 12

I get a line drawn between the points for Y1, but because there is not a Y2
value for every point on the X-axis then I just get points and no line,
despite a line being selected for in the options! Does anyone know how to get
this line added on?

Thanks