Excel 2010 - Data and dates not showing in line chart.

I have two sets of data, each on their own worksheet. There are 200+ lines of data collected on dates that is plotted on a line chart with two vertical axes.
One (Upp 1) plots just fine. The other (Upp 2) doesn't plot as it should.

I'm not able to get the data to show in the chart or the x axis to show the years (YYYY).
When I've tried to format the axis in the axis options but it is not showing showing "minimum", "maximum", etc options like it should...just "interval between tick marks", etc. like it is not recognizing there are dates - rather it appears to think the date data is a large number. When I right click the chart and click "select data", the horizontal axis labels show as the full dates (they show as years, YYYY, in the other worksheet as they should).
I tried switching to a scatter chart with partial success.
The file is attached.
Thank you in advance for your help.

Hi,

Try changing the chart type to XY Scatter.

I hope this helps

Hi,

I did try that...data plots, but the x axis is still messed up - not able to format it as dates.

Thank you.