Let's say you have 48-hours worth of data (I'm making this up, btw).
If you try to select these two columns and then click on Line Graph, here's what you get.
That's obviously not what we want. The trick is to use a Scatter Plot. I prefer Straight Marked Scatter.
And here's the final result.
I did have to make two changes.
- Vertically align the x-axis text
- Change the x-axis scale