Lookup a column value thats in my Temporary Table variable

Hi again,

ok. That unexpected error disappeared after reopening the file.

At the end the below is the solution.
I had to add one more line to your code.

Had to do this, because all filters where always (company, slicers....) ignored and only with that line:
If (isempty(invoice),blank(),..........)
it worked.

Actually I dont know why this is needed. I found it while googling but without any useful explanation. 
Can you explain, why this is needed?
Thank you and thank y for all your help with the code!