The first challenge is caused because when a month doesn't have a value it returns NULL. Adding any number to NULL returns NULL. You can change that by converting NULL to 0 when appropriate, for instance:
The second one seems like it's just a syntax error, this works:
The workbook is attached.
Hope that helps!
Mock File - KPI +- 150%_v10.2.twbx 794.9 KB
By the way, you can replace IFNULL(x,0) with the shortest ZN(x).
The Zero Null function does the same thing; if null then 0.
You can replace Adjustment Reason with
if isnull([Adjustment Reason]) then "" else [Adjustment Reason] end