Screwed up Trendline

Hello - I have a chart with two vertical axis tracking sales of 3 people. v-axis 1 tracks a bar chart for products and services. v-axis 2 tracks a trendline for weighted pipeline sales. Everything is correct except for 1 of my four trendlines. By looking at my chart you can see the total weighted sales has a problem with the data/line, whereby between the 3rd and 4th data point the trendline nosedives down to zero. I cannot figure out how I fixed the problem for the 3 other lines. The data for the screwed up line is in column F. Thank you anyone for your help.