You have replied to the original message on the thread, not to mine or even
to your own question. If you were trying to reply to a message of mine,
reply to that one and quote enough of it so that I and anyone else can see
the formula to which you are referring.
If I have guessed correctly what your talking about, and you are referring
to my reply of
=IF(A22>0,A22*A23+45,IF(A22=0,"","input negative and output undefined"))
[replacing the missing closing parenthesis which had got lost from my
reply], then my guess would be that you haven't actually got 0 in A22.
Try displaying some more decimal places in A22 to see what you've really
got. If you really had zero, the output of my formula would be an empty
string.
To get #VALUE! you've either got a string in A22, or a positive number in
A22 and a string in A23.