Help with graphing second data series.

I have a graph where the x axis is time (changes between 6A.M. - 8P.M. to 6P.M.-8A.M.) and y axis that, depending on the data selected, can go as high as 7000 (units vary in the legend). I have no problem with that graph, it's a smooth line scatter plot. I have other data, however, that gives one point: a time, and a corresponding percentage. What I'd like to do is have a vertical line that is at that corresponding time to be graphed on the same graph as my other data, with the legend describing what the percentage is. I'm not sure if this is possible. My graph has check boxes that allow me to select different parameters to be graphed, and their values aren't always similar (some values are as low as 100 to as high as 7000), hence why I want a vertical line to show the intersection at certain times. Anyone have any ideas on how I could do this?

Sure thing:
NorthvsSouth.xlsm

That is exactly what I am looking for, however, when I try to do it myself, it makes all of my other data change and now that won't graph horizontally now. This is the first time I've dealt with using secondary axis stuff.

That's the problem I'm running to and can't figure out. What did you do to the time value so that it would work out?
Here's the attempt I made:
NorthvsSouth.xlsm

Of course I would miss something so simple. Thanks for the help, much appreciated!