Why I am getting error "can not determine single value for column"?

[darkmetrics]

Good afternoon! I have a Sales table loaded to Power BI. It contains historical data about sales.

Following this guide (video_tutorial ).

I want to do the same as demonstrated in video. I want to separate positive and negative sales through DAX formula. So I right-click my mouse on the "Sales" table and select option "Create new meausure". After that I type the code for this measure like that (in line with recommendations from video tutorial):

Negative sales =
VAR SalesAmt = 'Sales table name '[Sales column name]
VAR Result = IF(SalesAmt < 0, SalesAmt, 0)
RETURN SalesAmt 

However, I am getting the error "can not determine single value Sales..." What I am doing wrong and why everything is ok in the video?

[johnt75 · Accepted solution]

In the video he is using a measure, not a column reference. You could define a measure like

Sales Amount = SUM('Sales table name '[Sales column name])

and then use that in the code instead of the column reference