Cell not populating - excel

Question

I have two cells that are refusing to populate in row 10 and 70. Every other cell populates and I have tried changing columns, even workbooks but I still get the same problem. There is no protection or passwords. I have no idea of the cause. This is the very simple code it is running on these cells:
i = 1
Worksheets("Output").Range("N1") = i
For z = 2 To lastrow - 1
If Worksheets("Output").Range("D" & z).Value < Worksheets("Output").Range("D" & z - 1).Value Then
i = i + 1
Worksheets("Output").Range("N" & z).Value = i
End If
If Worksheets("Output").Range("D" & z).Value = Worksheets("Output").Range("D" & z - 1).Value Then
Worksheets("Output").Range("N" & z).Value = i & " (tie)"
Worksheets("Output").Range("N" & z - 1).Value = i & " (tie)"
End If
If Worksheets("Output").Range("D" & z).Value = "" Then
i = i + 1
Worksheets("Output").Range("N" & z).Value = i
End If
Next z
I cannot fathom out why it is happening, the trouble is it messes up my sequence. I have tried forcing it to populate if it is blank with those last 3 lines but still nothing.

Answer 1

The principle error in your code is that it contains a logical trap:-
If [Condition 1] Then i = i + 1
If [Condition 2] Then i = i + 1
This is contrary to the logic that every row defined by z needs a result. The trap is in that nothing will be counted if neither of the two conditions are met. Therefore you should structure your code as follows.
If [Condition 1] Then
i = i + 1
ElseIf [Condition 2] Then
i = i + 1
Else
i = i - 1
End If
In this way, using Else, it will be impossible to skip a row.
However, there are more logical flaws in your code. and once I set out to determine what might be in column D I came to a totally different structure which I share with you below.
Sub STO_66111404()
Dim i As Long ' rank
Dim Tie As Boolean ' next item is of same value
Dim Tied As Boolean ' last item was of same value
Dim R As Long ' loop counter: rows
With Worksheets("Output")
For R = 1 To .Cells(.Rows.Count, "D").End(xlUp).Row - 1
i = i + Abs(Not Tie) ' Abs(Not Tie) = 1 if Tie is False
' Val() converts any non-numeric value, incl "", to 0
Tied = Tie
Tie = Val(.Cells(R, "D").Value) = Val(.Cells(R + 1, "D").Value)
.Cells(R, "N").Value = i & IIf(Tie Or Tied, " (tie)", "")
Next R
.Cells(R, "N").Value = i + Abs(Not Tie) & IIf(Tie, " (tie)", "")
End With
End Sub
It may take you a moment to recognize this code as your own. So, here are a few points to guide you.
With Worksheets("Output") helps you avoid repeating the sheet name over and over again. In the code that follows this line, and until End With, the object is represented merely by a leading period. .Cells(.Rows.Count, "D") stands for Worksheets("Output").Cells(Worksheets("Output").Rows.Count, "D")
Ranges comprising of single cells are most efficiently addressed by the syntax designed for that purpose, to wit, by a cell's coordinates instead of its range name. So, .Cells(R, "D") stands for Range("D" & R). This syntax has the added advantage that it is also equal to .Cells(R, 4), meaning you can easily calculate both row and column numbers.
The big difference in the approach is that your code focuses on the conditions and therefore uses a lot of IFs. In the above approach the focus is on the results of the conditions, expressed in the two variables, Tie and Tied. Your code has no equivalent for the latter but doesn't seem to need it, either. Note, however, that the above code may not handle the case correctly where the next value in column D is smaller than the preceding. The code just checks for equality and presumes that the next value is bigger if it isn't equal, setting Tie = False here: Tie = Val(.Cells(R, "D").Value) = Val(.Cells(R + 1, "D").Value). In your approach, this may be the reason for the skipped lines.