How to resolve VBScript error: Microsoft VBScript runtime error '800a0009' Subscript out of range: '[number: 21]'

I am really not good with VBscript, so hoping someone can help out.

I am trying to modify a record in a forum script using a simple form, but keep getting this following error:
Microsoft VBScript runtime  error '800a0009'
Subscript out of range: '[number: 21]'
/sdforum_modify.asp, line 70

Line 70 is:  MM_typeArray = Split(MM_columns(i+1),",")

in the file sdforurm_modify.asp, the whole section around this line is:

<%
' *** Update Record: construct a sql update statement and execute it

If (CStr(Request("MM_update")) <> "" And CStr(Request("MM_recordId")) <> "") Then

  ' create the sql update statement
  MM_editQuery = "update " & MM_editTable & " set "
  For i = LBound(MM_fields) To UBound(MM_fields) Step 2
    FormVal = MM_fields(i+1)
    MM_typeArray = Split(MM_columns(i+1),",")
    Delim = MM_typeArray(0)
    If (Delim = "none") Then Delim = ""
    AltVal = MM_typeArray(1)
    If (AltVal = "none") Then AltVal = ""
    EmptyVal = MM_typeArray(2)
    If (EmptyVal = "none") Then EmptyVal = ""
    If (FormVal = "") Then
      FormVal = EmptyVal
    Else
      If (AltVal <> "") Then
        FormVal = AltVal
      ElseIf (Delim = "'") Then  ' escape quotes
        FormVal = "'" & Replace(FormVal,"'","''") & "'"
      Else
        FormVal = Delim + FormVal + Delim
      End If
    End If
    If (i <> LBound(MM_fields)) Then
      MM_editQuery = MM_editQuery & ","
    End If
    MM_editQuery = MM_editQuery & MM_columns(i) & " = " & FormVal
  Next
  MM_editQuery = MM_editQuery & " where " & MM_editColumn & " = " & MM_recordId

  If (Not MM_abortEdit) Then
    ' execute the update
    Set MM_editCmd = Server.CreateObject("ADODB.Command")
    MM_editCmd.ActiveConnection = MM_editConnection
    MM_editCmd.CommandText = MM_editQuery
    MM_editCmd.Execute
    MM_editCmd.ActiveConnection.Close

    If (MM_editRedirectUrl <> "") Then
      Response.Redirect(MM_editRedirectUrl)
    End If
  End If

End If
%>

I would really appreciate any help.  I'm a novice at this.