I have been maintaining a spreadsheet for years. It is a very simple bar chart and one of the plotted data points occurs monthly and I had it displayed as a trend line that went from month to month. Today that trend line is gone but the dates at which the data is entered (monthly) are still colored. The connecting line has simply disappeared. I went into the data source and selected hidden cells and "connect data points with a line" is grayed out. I removed the monthly data source and then reentered the data with the same results. How can I get the trend line to be displayed again? Thank you.