I've done a lot of googling and no solution I've found works for me.
Under the screenshot I have translated what it says.
=IF(ISBLANK([ToDate]),"",[ToDate]-[DaysToWarn]
This only throws an syntax error. I've tried many different solutions but none of which seems to work.
I even built a replica in my test environment to see if that worked, which it did. I'm out of options and I don't know what I am doing wrong.
The problem, most likely, is due to the parameter separator. The documentation says:
All example formulas in this topic use commas
","
as the parameter delimiter character. In some countries, the comma is reserved for use as the decimal mark. In such countries, users creating a calculated field must use semi-colons";"
as the delimiter character.
If I'm correct to assume your localization is Swedish, the decimal separator is ','
(comma), and hence the parameter separator to be used shall be ';'
(semicolon).
=IF(ISBLANK([ToDate]); ""; [ToDate]-[DaysToWarn])