Letter Validation (prevents The Letters "I" Or "O")

i go to film school and i have created an excel spreadsheet to manage our shot list paperwork. in one column is the shot number (it's called the shot number, but letters are used instead.) i have applied a validation formula to the cells in that column (B9:B35) that prevents the letters "I" or "O" being entered (because I and O look like 1's and 0's, and therefore is not a "valid" shot number) prompting an error if the user does enter I or O. However, my formula doesn't work. right now i have =LEFT(B9:B35)= "A" which means that any text entered that begins with A will be accepted and other text will return an error. I want it so only the letters I or O return an error, and other letters don't prompt any error.