Try using the Exact function in your validation

for cell D4, I selected custom in validation and used this formula
=OR(EXACT($D$4,"X"),EXACT($D$4,"O"))

--
Regards,
Tom Ogilvy



"Henry" wrote:

Hello,

I made a validation to limit the user could input "O" and "X" only. However,
when the user hardcoded in lowercase, excel state that's an error. How can i
force the lowercase input to become uppercase? coz i would only see uppercase
on the cell.

Thanks,