Excel VBA code working except one computer - Error 91 - excel

Question

I have an Excel VBA sub that is used to search for contact details in Outlook.
The function is working on many computer except one that is the primary user of this function, on which it produces the error:
Error 91: Object variable or With block variable not set
Can someone help me please?
'Function to import Outlook contacts according to their client code
Sub ExportOutlookAddressBook()
Application.ScreenUpdating = False
Dim olApp As Outlook.Application
Dim olNS As Outlook.Namespace
Dim olAL As Outlook.AddressList
Dim olEntry As Outlook.AddressEntry
Dim CodeClient As String
Dim RCompanyName As String
Dim i As Integer
Dim AccountCount As Integer
Set olApp = Outlook.Application
Set olNS = olApp.GetNamespace("MAPI")
CodeClient = 0
RCompanyName = 0
i = 0
AccountCount = olNS.Accounts.Count
Range("AA6:AF10").ClearContents
For i = 1 To AccountCount
Set olAL = olNS.AddressLists(i) 'Change name if different contacts list name
Set olEntry = olAL.AddressEntries(1)
ActiveWorkbook.ActiveSheet.Range("K6").Select
CodeClient = ActiveCell.Value
ActiveWorkbook.ActiveSheet.Range("AA6").Select
For Each olEntry In olAL.AddressEntries
' your looping code here
RCompanyName = Left(Right(olEntry.GetContact.CompanyName, 7), 6)
If RCompanyName = CodeClient Then
ActiveCell.Value = olEntry.GetContact.FullName
ActiveCell.Offset(0, 1).Value = olEntry.GetContact.BusinessTelephoneNumber 'business phone number
ActiveCell.Offset(0, 2).Value = olEntry.Address 'email address
ActiveCell.Offset(0, 3).Value = olEntry.GetContact.CompanyName
ActiveCell.Offset(0, 4).Value = olEntry.GetContact.BusinessAddress
ActiveCell.Offset(1, 0).Select
End If
Next olEntry
Next i
Set olApp = Nothing
Set olNS = Nothing
Set olAL = Nothing
Application.ScreenUpdating = True
ActiveWorkbook.ActiveSheet.Range("K7").Select
End Sub

Answer 1

Try this.
Besides adding the If Nothing...'s, I tidied some of the other repetative code.
Option Explicit 'this line is recommended at the very top of every module.
'Function to import Outlook contacts according to their client code
Sub ExportOutlookAddressBook()
Dim olApp As Outlook.Application, olNS As Outlook.Namespace, olAL As Outlook.AddressList
Dim olEntry As Outlook.AddressEntry, CodeClient As String, RCompanyName As String, i As Long
Set olApp = Outlook.Application
Set olNS = olApp.GetNamespace("MAPI")
Application.ScreenUpdating = False
Range("AA6:AF10").ClearContents
For i = 1 To olNS.Accounts.Count
Set olAL = olNS.AddressLists(i) 'Change name if different contacts list name
Set olEntry = olAL.AddressEntries(1)
CodeClient = ActiveWorkbook.ActiveSheet.Range("K6")
ActiveWorkbook.ActiveSheet.Range("AA6").Select
For Each olEntry In olAL.AddressEntries
' your looping code here
RCompanyName = Left(Right(olEntry.GetContact.CompanyName, 7), 6)
If RCompanyName = CodeClient Then
With ActiveCell
.Value = olEntry.GetContact.FullName
.Offset(0, 1) = olEntry.GetContact.BusinessTelephoneNumber 'business phone number
.Offset(0, 2) = olEntry.Address 'email address
If Not olEntry.GetContact Is Nothing Then
If Not olEntry.GetContact.CompanyName Is Nothing Then
.Offset(0, 3) = olEntry.GetContact.CompanyName
End If
If Not olEntry.GetContact.BusinessAddress Is Nothing Then
.Offset(0, 4) = olEntry.GetContact.BusinessAddress
End If
End If
.Offset(1, 0).Select
End With
End If
Next olEntry
Next i
Set olApp = Nothing
Set olNS = Nothing
Set olAL = Nothing
Application.ScreenUpdating = True
ActiveWorkbook.ActiveSheet.Range("K7").Select
End Sub