PiPutVal giving 'index outside bounds of the array' in results

I'm trying to implement piputval in DataLink using some VB script I found on this site, but I keep ending up with 'Index was outside the bounds of the array.' for the output. When I check the PI tag in AF it is not being updated. The VB script is below.

Option Explicit

Public Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)

'This subroutine is called by the <Send above values> button on the
'left hand side of the "PutVal" worksheet
Sub put_data1()
   Dim i As Integer
   Dim numoftags As Integer
  
   'The following four variables are arguments to PIPutVal()
   Dim sTagname As String  'Tagname
   Dim stime As String     'Timestamp
   Dim sServer As String   'PI server name
   Dim valueCell As Range  'Cell reference containing value to be written
   Dim resultCell As Range 'Cell reference to hold result
   Dim apierr As Long
   Dim rowstr As String
   Dim buf As String
  
   Dim macroResult As Variant
   Dim timeCell As Range 'Cell reference to hold time of putval
  
   i = 0
   numoftags = 3  'we have three tags, from cell B4 to B6
   'server is in E8
   sServer = Worksheets("PutVal").Cells(8, 5).Text
   While i < numoftags
      'resultCell is in column 5 (E)
      Set resultCell = Worksheets("PutVal").Cells(i + 4, 5)
      'valueCell is in column 4 (D)
      Set valueCell = Worksheets("PutVal").Cells(i + 4, 4)
      'tagname is in column 3 (C)
      sTagname = Worksheets("PutVal").Cells(i + 4, 3).Text
      'timestamp is in column 2 (B)
      stime = Worksheets("PutVal").Cells(i + 4, 2).Text
    
      'Call the PIPutVal() macro function
      'Note that we pass just a , for the PIServer argument; i.e., we
      'are using the default PIServer
      macroResult = Application.Run("PIPutVal", sTagname, valueCell, stime, sServer, resultCell)
      'move down to the row number
      i = i + 1
   Wend
  
   Sleep (1000)
   i = 0
   While i < numoftags
      rowstr = Format(i + 4)
      buf = "G" & rowstr
      Range(buf).Select
      buf = "=PIExTimeVal($C$" & rowstr & ",$B" & rowstr & ",""" & sServer & """)"
      Selection.FormulaArray = buf
      i = i + 1
   Wend
End Sub