Excel VBA - Runtime error '1004' on If statement - vba

Question

I'm making a VBA program that changes the visuals of the excel file. There are some tags ("BN", "A", "C" etc.) which say how the rows/cells should be changed.
For example: the tag "A" means - set the cell font to "Arial", size 13... etc.
The program was working until I made some changes a while ago. Since then it's giving me always an runtime error. Has anyone any clue as to why?
The code:
Option Explicit
Sub macro1()
Dim rowIndex As Integer
Dim lastRowIndex As Integer
Dim offset As Integer
lastRowIndex = 2700
With ActiveSheet
For rowIndex = 1 To 3
Rows(1).EntireRow.Delete
Next rowIndex
With Cells.Font
.Name = "Arial"
.Size = 8
.Strikethrough = False
.Superscript = False
.Subscript = False
.OutlineFont = False
.Shadow = False
.Bold = False
.Underline = xlUnderlineStyleNone
.ColorIndex = 1
End With
With Cells
.RowHeight = 11
.HorizontalAlignment = xlLeft
.VerticalAlignment = xlBottom
.WrapText = False
.Orientation = 0
.AddIndent = False
.IndentLevel = 0
.ShrinkToFit = False
.ReadingOrder = xlContext
.MergeCells = False
End With
Columns(1).ColumnWidth = 13.5
Columns(2).ColumnWidth = 60
With Columns(3)
.HorizontalAlignment = xlCenter
.ColumnWidth = 5.5
End With
With Columns(4)
.HorizontalAlignment = xlRight
.ColumnWidth = 6.5
End With
With Columns(5)
.HorizontalAlignment = xlRight
.ColumnWidth = 6.5
End With
Columns(4).HorizontalAlignment = xlRight
Columns(5).HorizontalAlignment = xlRight
rowIndex = 1
offset = 0
Do While (rowIndex - offset) < lastRowIndex
If Cells(rowIndex, 5).Value = "A" Or Cells(rowIndex, 5).Value = "NAZOV" Or _
Cells(rowIndex, 5).Value = "C" Or Cells(rowIndex, 6).Value = "BN" Then
If Cells(rowIndex, 5).Value = "A" Then
Cells(rowIndex, 5).ClearContents
With Cells(rowIndex, 2).Font
.Name = "Arial Narrow"
.Size = 11
.Bold = True
.Color = RGB(204, 0, 0)
End With
With Cells(rowIndex, 2)
.RowHeight = 16
.HorizontalAlignment = xlCenter
End With
End If
If Cells(rowIndex, 5).Value = "NAZOV" Then
Cells(rowIndex, 5).ClearContents
With Cells(rowIndex, 2).Font
.Name = "Arial"
.Size = 9
.Bold = True
.Underline = xlUnderlineStyleSingle
.Color = RGB(0, 0, 153)
End With
With Cells(rowIndex, 2)
.RowHeight = 13
End With
End If
If Cells(rowIndex, 5).Value = "C" Then
Cells(rowIndex, 5).ClearContents
Cells(rowIndex, 6).ClearContents
Cells(rowIndex, 7).ClearContents
With Cells(rowIndex, 2).Font
.Name = "Arial Narrow"
.Size = 8
.Italic = True
.ColorIndex = 16
End With
With Cells(rowIndex, 2)
.RowHeight = 12
End With
End If
If Cells(rowIndex, 6) = "BN" Then
Cells(rowIndex, 6).ClearContents
If (Cells(rowIndex + 1, 5) <> "C") Then
Rows(rowIndex + 1).Insert
With Rows(rowIndex + 1)
.RowHeight = 3
.Font.Size = 2
End With
offset = offset + 1
Else
Rows(rowIndex + 2).Insert
With Rows(rowIndex + 2)
.RowHeight = 3
.Font.Size = 2
End With
offset = offset + 2
End If
End If
Else
Cells(rowIndex, 2).WrapText = True
Rows(rowIndex).AutoFit
End If
If Cells(rowIndex, 6).Value = "D" Then
Cells(rowIndex, 6).ClearContents
With Selection.Font
.Underline = xlUnderlineStyleSingle
.Bold = True
.Italic = False
End With
End If
If Cells(rowIndex, 6).Value = "E" Then
With Selection.Font
.Underline = xlUnderlineStyleSingle
.Bold = False
End With
End If
If Cells(rowIndex, 5).Value = "P" Then
Cells(rowIndex, 5).ClearContens
End If
If ( _
((Cells(rowIndex, 5) = Cells(rowIndex - 1, 5)) Or (Cells(rowIndex, 5) = Cells(rowIndex - 2, 5))) And _
((Cells(rowIndex, 4) = "" And Cells(rowIndex - 1, 4) <> "") Or (InStr(Cells(rowIndex, 2).Text, ">"))) And _
(Cells(rowIndex - 1, 2).Font.Size = 9) Or (Cells(rowIndex, 2).Font.Size = 9 And Cells(rowIndex - 1, 2).Font.Size = 9)) Then
With Cells(rowIndex, 2).Font
.Italic = True
.ColorIndex = 16
.Bold = False
.Size = 8
.Underline = False
End With
Cells(rowIndex, 2).WrapText = True
Rows(rowIndex).AutoFit
End If
rowIndex = rowIndex + 1
Loop
End With
End Sub
The runtime error appears on the last IF statement:
If ( _
((Cells(rowIndex, 5) = Cells(rowIndex - 1, 5)) Or (Cells(rowIndex, 5) = Cells(rowIndex - 2, 5))) And _
((Cells(rowIndex, 4) = "" And Cells(rowIndex - 1, 4) <> "") Or (InStr(Cells(rowIndex, 2).Text, ">"))) And _
(Cells(rowIndex - 1, 2).Font.Size = 9) Or (Cells(rowIndex, 2).Font.Size = 9 And Cells(rowIndex - 1, 2).Font.Size = 9)) Then