Why is my loop skipping a cell in the below code? - excel

Question

I'm making a VBA macro to concatenate a number given by the user with a previous column value. Once the loop gets to the value given by the user (the top value), the loop would start again since number one. By now my loop gets to the top value and starts from one, but every time this happened the code skip to the next cell, could you tell me why is this happening guys? (down value by default).
Sorry i'm a little bit new on VBA, here is my try:
Sub Balance()
Dim myValue As Integer
myValue = InputBox("Please, give me a number")
Range("A2").Select
Range("A:A,C:C,F:F,H:J,L:L,T:T,W:X").Delete
Range("A2").Select
firstrow = ActiveCell.Row
Selection.End(xlDown).Select
lastrow = ActiveCell.Row
For i = 1 To lastrow
If Range("M" & i) = "AB" Then
For j = 1 To myValue
watcher = j
Range("N" & i) = "TV" & " " & Range("M" & i) & " " & watcher
i = i + 1
Next j
End If
Next i
End Sub
This the output with the number 10 as input (Column N):
I would like to reach this goal:

Answer 1

You already have your answer by Vandear explaining why the row is getting skipped. However here is an alternative way using only one loop to achieve what you want. But before that couple of suggestions
Suggestions:
Use Option Explicit and declare your variables. You may want to see Optimizing the VBA Code and improve the performance
Avoid the use of Select/Activate You may want to see How to avoid using Select in Excel VBA
Avoid the use of xlDown to get the last row. You may want to see Finding Last Row
When accepting number from users, use Application.InputBox with a Type:=1 instead of just InputBox. This way you will only restrict numbers.
Is this what you are trying?
Code:
Option Explicit
Sub Balance()
Dim ws As Worksheet
Dim lRow As Long
Dim i As Long, counter As Long
Dim myValue As Long
myValue = Application.InputBox(Prompt:="Please, give me a number", Type:=1)
If myValue < 1 Then Exit Sub
'~~> Change this to the relevant sheet
Set ws = Sheet1
With ws
'~~> For demonstration below. I did not use this line below. But
'~~> If you need to delete those columns then use it this way
.Range("A:A,C:C,F:F,H:J,L:L,T:T,W:X").Delete
lRow = .Range("A" & .Rows.Count).End(xlUp).Row
'~~> Set your counter
counter = 1
For i = 1 To lRow
If .Range("M" & i) = "AB" Then
Range("N" & i) = "TV" & " " & .Range("M" & i).Value2 & " " & counter
counter = counter + 1
'~~> Reset your counter if it crosses user input
If counter > myValue Then counter = 1
End If
Next i
End With
End Sub
In action:

Answer 2

Couple of things before I answer your problem:
It's advisable to declare your variables for better structure:
Dim i As Integer, j As Integer, MyValue As Integer, firstrow As Integer, lastrow As Integer
You can skip the selection of a cell and directly reference it:
firstrow = Range("A2").Row
lastrow = Range("A2").End(xlDown).Row
The Answer to your Problem:
When the code exits the for-next loop for j, i is increased by 1 (i=i+1), and then it will be increased again by 1 when it proceeds to the next i line. This is the reason why it skips to the next row. So after the for-next loop for j, you need to decrease i by 1 before proceeding to the for-next loop for i.
For i = 1 To lastrow
If Range("M" & i) = "AB" Then
For j = 1 To myValue
watcher = j
Range("N" & i) = "TV" & " " & Range("M" & i) & " " & watcher
i = i + 1
Next j
i=i-1 <-------
End If
Next i