HLookup formula. Pretty basic. It's looking for 50, 70, Q or H as the header of some columns. 50, 70, Q or H are something you'd enter into a specific cell, then it would look for resulting values. 50, 70 and Q all worked fine. H returned "#N/A". First thought was "maybe this function doesn't like mixing numbers and letters as the column headers", but nope, I was mixing them and 50, 70 and Q all worked. Maybe the format for H is somehow different? So I copied the formal for Q into H. Still #N/A. I experimented a bit. Substituting T for H worked fine. Same for X, Same for another couple of letters. So I just changed the header to "X" and it's all fine now. But what would be the reason for H NOT to work, but pretty much any other letter was fine? Did using "H" in an "HLookup" somehow confuse the function?