Got warning message.

Hi Ned,
I got a warning message after I added Reviews/Sales into the Rows (screenshot #1).

Also, the shape of the line graph was different from that one in the video ( screenshot #1).

Only after I click on the link icon on the right of Transaction ID (primary key), the shape of the line and info on the X axis became like those in the videos (Screenshot #2).

Could you explain why?

Thank you,
M.