Excel VBA that uses nested If statements for multiple worksheets - excel

Question

I'm trying to get an output in column U for multiple worksheets in a workbook. The return string will either be "Yes" or "No" depending on which column is not blank and if the difference between two dates are > 150. This is the code I have written, but nothing shows up in column U. Could anyone help me figure out why this isn't working?
Sub Compliance()
Dim ws As Worksheet
For Each ws In ThisWorkbook.Worksheets
Dim i As Integer
Dim listLength
listLength = ws.Cells(Rows.Count, "M").End(xlUp).Row - 1
For i = 2 To listLength + 2
If IsEmpty(ws.Range("P" & i)) = True And IsEmpty(ws.Range("O" & i)) = True And IsEmpty(ws.Range("N" & i)) = True And DateDiff("d", ws.Range("M" & i), ws.Range("K" & i)) > 150 Then
ws.Range("U" & i) = "Yes"
ElseIf IsEmpty(ws.Range("P" & i)) = True And IsEmpty(ws.Range("O" & i)) = True And DateDiff("d", ws.Range("N" & i), ws.Range("M" & i)) < 150 Then
ws.Range("U" & i) = "Yes"
ElseIf IsEmpty(ws.Range("P" & i)) = True And DateDiff("d", ws.Range("O" & i), ws.Range("N" & i)) < 150 Then
ws.Range("U" & i) = "Yes"
ElseIf DateDiff("d", ws.Range("N" & i), ws.Range("M" & i)) < 150 Then
ws.Range("U" & i) = "Yes"
Else
ws.Range("U" & i) = "No"
End If
Next
Next ws
End Sub

Answer 1

When you start your loop with For Each ws In ThisWorkbook.Worksheets then Excel starts processing from Sheet1 and I'm sure your list in another sheet.
So, the reason nothing changes in your U column is, because you are
looking at wrong Worksheet.
As long as you would like to loop through all of your worksheets, start to follow your lists from Sheet1. If you would like to loop in different order, you should define this in your code.
And below I edited some part of your code and also added msgbox ws.name to show you in which sheet Excel is working now.
Why Use Integer Instead of Long?
Option Explicit
Sub Compliance()
Dim ws As Worksheet
For Each ws In ThisWorkbook.Worksheets
Dim i As Long
Dim listLength
MsgBox ws.Name
listLength = ws.Cells(ws.Rows.Count, "M").End(xlUp).Row - 1
For i = 2 To listLength + 2
If IsEmpty(ws.Range("P" & i)) = True And IsEmpty(ws.Range("O" & i)) = True And IsEmpty(ws.Range("N" & i)) = True And DateDiff("d", ws.Range("M" & i), ws.Range("K" & i)) > 150 Then
ws.Range("U" & i) = "Yes"
ElseIf IsEmpty(ws.Range("P" & i)) = True And IsEmpty(ws.Range("O" & i)) = True And DateDiff("d", ws.Range("N" & i), ws.Range("M" & i)) < 150 Then
ws.Range("U" & i) = "Yes"
ElseIf IsEmpty(ws.Range("P" & i)) = True And DateDiff("d", ws.Range("O" & i), ws.Range("N" & i)) < 150 Then
ws.Range("U" & i) = "Yes"
ElseIf DateDiff("d", ws.Range("N" & i), ws.Range("M" & i)) < 150 Then
ws.Range("U" & i) = "Yes"
Else
ws.Range("U" & i) = "No"
End If
Next
Next ws
End Sub