This question already has an answer here:
When I try to use the following expression, the preview shows me the correct sum, but when I click ok I get this notification. This tells me it can't calculate column "Subsidie J"
It seems that it can't find the value for column "Subsidie J" but it's all in the attribute table.
Am I using the wrong expression? The value of "Subsidie J" is a CASE IF .... THEN ... END expression. Now I want the sum of these values sorted by owner.