Need a set of eyes to find what I can't

I would really appreciate someone taking a look at this code. I wrote it to go through a bill of materials and match a regular expression pattern to identify certain items and generate a cut list. I'm not really getting any compile errors, but it's also not doing anything at all when it's run. This code is all placed within a module:

Option Explicit

Dim Pattern(1 To 12) As String             'Array of patterns

Dim CellRead As Range
Dim CellWrite As Range

Dim RowCntRead As Integer
Dim RowCntWrite As Integer
Dim ColCntRead As Integer
Dim ColCntWrite As Integer

Sub InitializeArray()

Pattern(1) = "-*"
Pattern(2) = "TS\d*|HSS\d*"
Pattern(3) = "L\d*"
Pattern(4) = "C\d*"
Pattern(5) = "MC\d*"
Pattern(6) = "W\d*"
Pattern(7) = "\d+W\d|GRATE|GRATING"
Pattern(8) = "D\d*"
Pattern(9) = "CF\d*"
Pattern(10) = "FB\d*"
Pattern(11) = "EXP\d*"

End Sub

Function IndexNumber(ByVal InputString As String)

Dim i As Integer            'Pattern index

For i = 1 To UBound(Pattern)
    With CreateObject("VBScript.RegExp")
        .Global = False
        .IgnoreCase = True
        .Pattern = Pattern(i)
        
        If .Test(InputString) Then
            IndexNumber = i
            Exit Function
            
        End If
    End With
Next i
    
IndexNumber = 0
End Function

Function SplitString(ByRef InputString As String, ByVal i As Integer, ByVal Element As Integer)

Dim SplitArray() As String      'Array of substrings

With CreateObject("VBScript.RegExp")
        .Global = False
        .IgnoreCase = True
        .Pattern = Pattern(i)
        
    If .Test(InputString) Then
        InputString = .Replace(InputString, "|")
        SplitArray = Split(InputString, "|")
        SplitString = SplitArray(Element)
        Exit Function
    End If
    
End With

SplitString = "--"

End Function

Private Sub NextCellWrite()

ColCntWrite = ColCntWrite + 1
Set CellWrite = Sheets("CUT LIST").Cells(RowCntWrite, ColCntWrite)

End Sub

Sub SetCellRead()

Set CellRead = Sheets("BOM").Cells(RowCntRead, ColCntRead)

End Sub

Sub SetCellWrite()

Set CellWrite = Sheets("CUT LIST").Cells(RowCntWrite, ColCntWrite)

End Sub

Private Sub PopulateCutList_Click()

InitializeArray

Dim PatternNo As Integer                'Pattern identification number
Dim i As Integer                        'Pattern parse count
Dim CellReadTimeout As Integer

Dim DetailNo As Variant
Dim MaterialType As String
Dim MaterialSpec As String
Dim JobQty As Integer
Dim CutLength As String
Dim CutCode As String

'   ***Initialize***

RowCntRead = 2
RowCntWrite = 4
ColCntRead = 3
ColCntWrite = 1

CellReadTimeout = 0

Set CellRead = Sheets("BOM").Cells(RowCntRead, ColCntRead)
Set CellWrite = Sheets("CUT LIST").Cells(RowCntWrite, ColCntWrite)

'------------------------------------------------------------------

For i = 2 To UBound(Pattern)

    Do While CellReadTimeout < 5

        PatternNo = IndexNumber(CellRead.Value)
    
    
        If CellRead.Value <> "" Then
    
            If PatternNo = i Then

                Select Case PatternNo
    
                    Case 2
                        MaterialType = "TUBE STEEL (TS)"
            
                    Case 3
                        MaterialType = "ANGLE (L)"
            
                    Case 4
                        MaterialType = "C-CHANNEL (C)"
            
                    Case 5
                        MaterialType = "MC CHANNEL (MC)"
                                                
                    Case 6
                        MaterialType = "WIDE FLANGE BEAM (W)"
                    
                    Case 7
                        MaterialType = "STEEL BAR GRATING, WELDED"
                        
                    Case 8
                        MaterialType = "ROUND TUBE"
                        
                    Case 9
                        MaterialType = "ROUND BAR"
                        
                    Case 10
                        MaterialType = "FLAT BAR"
                        
                    Case 11
                        MaterialType = "EXPANDED METAL"
            
                End Select
    
                ColCntRead = 4
                SetCellRead
                DetailNo = Trim(SplitString(CellRead.Value, 4, 0))
                CutCode = Trim(SplitString(CellRead.Value, 4, 1))
                
                ColCntRead = 6
                SetCellRead
                JobQty = CellRead.Value
                
                ColCntRead = 8
                SetCellRead
                CutLength = CellRead.Value
                
                ColCntRead = 3
                SetCellRead
                MaterialSpec = CellRead.Value
    

                CellWrite.Value = DetailNo
                NextCellWrite
                CellWrite.Value = MaterialType
                NextCellWrite
                CellWrite.Value = MaterialSpec
                NextCellWrite
                CellWrite.Value = JobQty
                NextCellWrite
                CellWrite.Value = CutLength
                NextCellWrite
                CellWrite.Value = CutCode
        
                RowCntWrite = RowCntWrite + 1
                ColCntWrite = 1

                CellReadTimeout = 0
        
            End If
    
            RowCntRead = RowCntRead + 1
            SetCellRead
    
        Else:

            RowCntRead = RowCntRead + 1
            SetCellRead
            
            CellReadTimeout = CellReadTimeout + 1
            
        End If
    
    Loop
    
RowCntRead = 2
SetCellRead
RowCntWrite = RowCntWrite + 2
SetCellWrite

Next i

End Sub

Private Sub ClearBOM_Click()

ThisWorkbook.Worksheets("BOM").Range("A1:J500").ClearContents

End Sub

Private Sub ClearCutList_Click()

ThisWorkbook.Worksheets("CUT LIST").Range("A3:F500").ClearContents

End Sub

Also, if there's any way I could break this code up to make it clearer for you to read in the forum, please let me know.