Display message when data points exceed reference line

Hi weijunawj 

In addition to amitchandak's reply, I will show the way in details.

Firstly, I need to know how did you get the reference line. Is it an average line in visual analysis?

If you want to show different colors to distinguish whether the value exceeds the average, build a measure as below.

Color = 
VAR _AVERAGE = CALCULATE(AVERAGE('Table'[Value]),ALL('Table'))
RETURN
IF(SUM('Table'[Value])>_AVERAGE,"RED","BLUE")

Build a bar chart and use FX in Data color in Format.

Select Field value in Format by and based on color measure. Then select ok and transform the bar chart to line chart.

Result is as below.

If you need to a tooltip to show whether the value exceeds the average, you can change the result in color measure and add this measure into tooltips in this visual.

Tooltips = 
VAR _AVERAGE = CALCULATE(AVERAGE('Table'[Value]),ALL('Table'))
RETURN
IF(SUM('Table'[Value])>_AVERAGE,"Above Avg","Below Avg")

To see the  tooltip, you need to hang your mouse on the point in line chart. Or the tooltips will be hidden.

You can build a tooltip based on report page as well. 

For reference: Create tooltips based on report pages in Power BI Desktop

Best Regards,

Rico Zhou

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