Update, I am a little closer. This formula doesn't throw an error, but also doesn't return a correct count.
=COUNTIF($A$4:$AB$54,TEXT(AD5,""+TEXT(OFFSET(Selec tion,0,1,1,1),"x")))

I think the problem is Excel needs to know which cell from which to offset. "Selection" does not seem to do the trick. So, maybe I need to know how to detect each cell as CountIF() iterates through the range. Am I on the right track?

Thanks