XY Scatter Plot: drawing ines connection data points

[RGButzArchInc]

I have followed MS explanatory to no avail. I have created a Scatter diagram showing smoothed lines thru the data points with the highlighted data points in my spread sheet.. However, lines do not appear. Thank you id advance for your suggestion(s).

 

[Worf]

What Excel version are you using? Windows or Mac?
A scatter plot with smooth lines and markers is a standard option, did you use that?
Maybe your line is white.