Help With Expression Error Message

[drogersdk]

Hello, I'm a brand new user attempting to work through the book "Teach Yourself Visually Power BI" by Alexander Loth. One of the first exercises is to remove duplicate values. The book instructs me to download an excel file (https://learn.microsoft.com/bs-latn-ba/power-bi/create-reports/sample-financial-download) and to save it to C:\Power BI. It also links to Power BI files on the Wiley website (https://www.wiley.com/en-us/Teach+Yourself+VISUALLY+Power+BI-p-9781119903772).

The book instructs me to open the file "Chapter 3 - Remove Duplicates.pbix" from the Wiley downloads and then to click Transform Data. When I do this I get the following error:

I'm not sure what this means or what I've done wrong. Also, why am I being told to save to a specific folder on my C: drive that I had to create manually? Do these files need to be saved near the program on my hard drive?

Any help is appreciated.

[wdx223_Daniel]

it looks like you are refering a table that not exists.

check your Source step, if there are a row which Item column value is "Table1" and Kind column value is "Table"