Hi Nadine,

I'm glad to hear that you found a solution to your problem by using the draw function to manually draw a line where you wanted it. However, if you ever need to highlight a specific gridline on the axis scale in the future, you can follow these steps:

1. Select the chart that you want to modify.
2. Right-click on the axis that you want to modify and select "Format Axis" from the drop-down menu.
3. In the Format Axis pane that appears on the right-hand side of the screen, click on the "Axis Options" tab.
4. Under "Axis Options", scroll down to the "Axis Position" section and select "On Tick Marks" from the drop-down menu.
5. Scroll down to the "Tick Marks" section and select "Inside" or "Outside" from the drop-down menu to specify where you want the tick marks to appear.
6. Scroll down to the "Major Tick Mark Type" section and select "Cross" from the drop-down menu to specify the type of tick mark that you want to use.
7. Scroll down to the "Major Tick Mark Color" section and select the color that you want to use for the tick mark.

These steps will allow you to highlight a specific gridline on the axis scale by changing the color of the tick mark. I hope this helps, but please let me know if you have any further questions!