xlLastCell only works half of the time - ms-access

Question

I am trying to remove the duplicates in excel via the following code:
Set rng = Range("A1", Range("A1").SpecialCells(xlLastCell))
rng.removeduplicates Columns:=8, Header:=xlYes
This method seems to work half of the time. Sometimes it works, sometimes it gives me the following error:
Searching on run-time error 1004 gives me the info that there shouldn't be strings, with more than 911 chars, which is not the case. When running the code multiple times on the same excel file, it goes well around 50 percent of the time.
I am running the code in ms access 2007, but all my references are switched on. The question is ofcourse, how to solve this, but any other, better way to easily remove my duplicates will be appreciated as well. Thank you.
EDIT: Full code:
Const xlLastCell As Long = 11
Const xlYes As Long = 1
Public Function formatreports(FileName As String) As String
Dim xl As Excel.Application
Dim xlwb As Excel.Workbook
Dim xlsh As Excel.Worksheet
Dim rng As Range
Dim newname As String
Set xl = CreateObject("Excel.Application")
xl.DisplayAlerts = False
xl.Visible = False
Set xlwb = xl.Workbooks.Open(FileName)
Set xlsh = xlwb.Worksheets(1)
'its MFR0004; This is solely for import reasons
xlsh.Rows("1:4").Delete
xlsh.Rows("2").Delete
xlsh.Columns("A:B").Delete
xlsh.Columns("B").Delete
'This as well
xlsh.Range("J1") = "Total Weight"
xlsh.Range("L1") = "Net Weight"
xlsh.Range("O1") = "Gross Weight"
xlsh.Range("AA1") = "Delivery Date"
Set rng = xlsh.Range("A1", Range("A1").SpecialCells(xlLastCell))
rng.removeduplicates Columns:=8, Header:=xlYes
newname = Left(FileName, Len(FileName) - 4) & ".XLSX"
xlwb.SaveAs newname, FileFormat:=51
formatreports = newname
xlwb.Save
xlwb.Close
xl.Quit
Set xl = Nothing
End Function

Answer 1

The problem is that your cells are not fully qualified.
You need to try something like this
' change sheet1 to the relevant worksheet
With ThisWorkbook.Sheets("Sheet1")
Set rng = .Range("A1", .Range("A1").SpecialCells(xlLastCell))
rng.RemoveDuplicates Columns:=8, Header:=xlYes
End With
On A side note: Since you are saying that you are working from Access and this code works sometime that means you are maybe using Early Binding. If you are not then you will have to add these to the top of your code
Const xlLastCell As Long = 11
Const xlYes As Long = 1