It’s not clear to me what the original input is, and what the edit you made is. I understand that it has something to do with H23-O17, and I see the comment you made in the input file.
My best guess is that you’re saying you’re trying to change the first water into the second water. That won’t work because the oxygen is trying to refer to an atom that doesn’t exist yet. It’s atom 21, so it can only use atoms 1-20.
Also, please enclose your input files in backticks, per our advice on asking questions.