I am guessing that you either have a data issue, or have an error in how you applied it.
This can be shown to work properly pretty easily on a new blank sheet.
First, let's test one where there is a match, so nothing should be returned.
1. Place the formula in cell D1 on your sheet:
Code:
=IF(COUNTIF(C14:C62,C2)=0,1,"")
2. Place an "a" in cell C14
3. Place an "a" in cell C2
The formula should return nothing.
Now, let's test where there is no match. We can use the same sheet.
Simply change the value in cell C2 from "a" to "b".
You will now see "1" show up in cell D1.
So the formula is doing what you asked in both cases.
Note that something as simple as an extra space will cause things not to match, i.e. "a " will not match "a".
They must be EXACTLY the same.