I am using COUNTIF to count the various values in a column. There are 9 different values in a column of 47 rows. Two of these values contain parentheses.

The function returns 0(zero) for these values only. I suspect it is because of the parentheses. I have even tried copy & paste a cell's content into the formula with identical results. Is this a bug, or is there an escape character I should be using?