Hello Gishara Premarathne,
I'm unable to open your workbook, it results in an error.
However I might be able to shed some light here: Are you Geo pills set to "computed using -> [Point (bin)]"?
I invite you to right click on your lat/lon pills in the rows/Columns and use this setting.
Let me know if it helped you!
Thanks for the reply. I am already using the settings to "computed using -> [Point (bin)]" for lat/lon fields. But still it does not generate a curve, bu it shows number of points on the connecting line. (of origin-destination)