Need help with calulator

im trying to use the calculator and keep it 50/50 and no nic but im sure how it keeps telling that my my percentages are wrong so any pointers??

Fill out “Amount to make”, then put 0 in “Desired strength”. Put 50 in “Desired PG”, and the “Desired VG” will auto update. Then just add flavors and input percentages. If you get a red error, then you’re using too much flavoring (over 50%). Flavoring will count as PG per default.