Need help figuring out how to check multiple cells for a single (at least one) instance of a capital letter? So I thought I would use something like this

=IF(OR(COUNTIF(AU51:AU60,"D")=0,COUNTIF(AU155:AU158,"D")=0),"D","")

but the problem is that some of the cells can also contain a lower case "d", so the check is failing...and again, all I need to make sure is that there is at least one capital "D" in any of the cells. Thanks!