Changing cell color from an if statement

You need 2 conditional formatting statements. I deleted the ones that you had in there. You can use formulas in conditional formatting but in this case you do not have to. (Formulas within cells do not ever, by themselves, affect cell formatting).

1. New Rule> Format only cells that contain> [Cell Value] [greater than] [=A15] Format as red, OK
2. New Rule> Format only Cells that contain> [Cell Value] [less than or equal to] [A15] Format as green, OK
See attachment